purlJam

<planning>
1. **Design Strategy**: The user wants a "butterfly cardigan" at beginner level, worked in worsted weight yarn. I need to interpret "butterfly" as a design element — the most natural interpretation for a beginner knit is a butterfly stitch motif or butterfly-themed aesthetic. Since this is beginner level, I'll use a simple **butterfly stitch** (a slip-stitch texture that creates gathered "wing" shapes — worked every 6th row by catching loose strands) on the body panels, which is actually quite achievable for beginners. The overall construction stays true to the Basic Stockinette Cardigan template. I'll add butterfly motif as an allover texture on the body (not sleeves, to keep it simpler), and keep sleeves in plain stockinette. Colorway suggestion: soft, nature-inspired. The butterfly stitch repeat is a multiple of 10 sts + 7, but I need to reconcile this with rib multiples of 4. I'll plan carefully. Actually, for true beginner simplicity, I'll use a simpler approach: butterfly slip-stitch that works on a multiple of 10 sts + 7. Let me reconsider — I want to keep the beginner accessible. I'll use a simplified butterfly stitch that works on a multiple of 10 + 5, which I can adapt. Let me define the butterfly stitch pattern clearly.

   **Butterfly Stitch Definition**: Classic butterfly stitch = multiple of 10 + 7. Every RS row 1-9 you slip stitches with yarn in front, and on row 10 you catch them. This is actually manageable for beginners if explained clearly. However, I need to make stitch counts work. Let me use multiple of 10 + 7 for the body sections. 

   Actually, to keep it truly beginner, let me use a simpler interpretation: a **mock butterfly** using yarn-overs and decreases to suggest wing shapes, OR keep it as a slip-stitch butterfly which is genuinely beginner-friendly (no complex techniques). I'll go with slip-stitch butterfly — it looks impressive but is easy.

   The butterfly stitch repeat: 10 sts + 7 (e.g., 47, 57, 67, 77, 87 sts work). I need to plan sizes so back stitch counts fit this multiple.

2. **Construction Plan**: Worked flat in pieces (back, left front, right front, two sleeves), bottom-up, seamed. 
   - Ribbing: 2×2 rib (multiple of 4) on cuffs and hem
   - Body: Butterfly slip-stitch pattern
   - Sleeves: Stockinette (simpler for beginner)
   - Button bands picked up after seaming
   - 5 sizes: XS, S, M, L, XL

   **Sizing** (finished bust measurements with approx 2" positive ease):
   - XS: 36" finished (fits 34" bust)
   - S: 40" finished (fits 38" bust)
   - M: 44" finished (fits 42" bust)
   - L: 48" finished (fits 46" bust)
   - XL: 52" finished (fits 50" bust)

   **Gauge**: 20 sts × 26 rows = 4" (10 cm) in stockinette on US 7 / 4.5 mm needles.
   So: 5 sts per inch, 6.5 rows per inch.

   **Key measurements**:
   - Body length to underarm: 14" (all sizes, adjustable)
   - Armhole depth: 7 (7.5, 8, 8.5, 9)"
   - Back neck width: 6 (6.5, 7, 7, 7.5)"
   - Sleeve length: 17" (adjustable)
   - Cuff circumference: 9 (9, 10, 10, 11)"

   **Stitch Counts** (at 5 sts/inch):

   BACK:
   - XS: 36" total, back = 18", 18 × 5 = 90 sts → need multiple of 10 + 7: 87 or 97. 87 = 8×10+7 ✓. Close to 90, use 87. That gives 87/5 = 17.4" ≈ 17.4" back width. Hmm, let me reconsider.
   
   Actually, let me think about this differently. The butterfly stitch is on the RS-facing fabric body. For the back piece, the stitch count needs to be (10n + 7). For fronts, each front is roughly half the back width, so around (10n + 7)/2... this gets complicated. 

   Let me reconsider the butterfly stitch multiple. Some versions are multiples of 10 + 5, or I can use a different multiple. Let me use a butterfly stitch that's a multiple of 8 + 7, which is more flexible. Actually the classic is 10+7. 

   Alternatively, I could center the butterfly stitch pattern and work plain stockinette at the sides. This is actually more practical for a cardigan — center butterfly panel flanked by stockinette. This also helps with side shaping math.

   Better approach: Work butterfly stitch in the center of each piece, with a few stitches of stockinette at each edge. This way the stitch counts don't need to be exact multiples.

   Let me define:
   - Edge stitches: 2 sts stockinette each side on back (seam sts)
   - Center stitches: butterfly pattern (10n + 7)
   - Total back = 2 + (10n+7) + 2 = 10n + 11

   For sizing:
   - XS back: ~87 sts → 87 - 4 = 83 center sts. 83 = 10(7)+7+6... not clean. 
   
   OK, I'm overcomplicating this. Let me use a slightly different approach:

   **Simplified approach**: The butterfly stitch will be described as working across the full width with the stitch count adjusted to fit. I'll note that edge stitches (first and last 2 sts) are always knit, and the butterfly pattern fills the middle. The butterfly stitch I'll use has a repeat of 10 sts, so:

   Total sts = 4 (edges) + 10n + 7 (pattern) = 10n + 11

   Sizes:
   - XS: n=8 → 91 sts = 91/5 = 18.2" back → full bust = 36.4" ✓ (target 36")
   - S: n=9 → 101 sts = 20.2" back → full bust = 40.4" ✓ (target 40")
   - M: n=11 → 121 sts = 24.2" back → full bust = 48.4"... too big for M
   
   Hmm, let me try n=10 → 111 sts = 22.2" → bust = 44.4" ✓ for M
   n=11 → 121 sts = 24.2" → bust = 48.4" ✓ for L  
   n=12 → 131 sts = 26.2" → bust = 52.4" ✓ for XL

   So back stitch counts: 91 (101, 111, 121, 131)
   These are back widths: 18.2 (20.2, 22.2, 24.2, 26.2)"
   Full bust (2× back): 36.4 (40.4, 44.4, 48.4, 52.4)" ✓

   Wait, for a cardigan, the full circumference = back + left front + right front. Each front is roughly half the back width (for a straight cardigan). So:
   - Front width = back width / 2 = 9.1 (10.1, 11.1, 12.1, 13.1)"
   - Front sts = back sts / 2 = 45.5 (50.5, 55.5, 60.5, 65.5)...

   These don't divide cleanly into multiples. Let me reconsider.

   Actually, for a cardigan, the back = half the total circumference, and each front = 1/4 of the circumference (the two fronts together = back width, accounting for button band overlap). So fronts can be about 45-46 sts for XS.

   For fronts, the butterfly stitch pattern continues, but fronts are narrower. I can use fewer repeats:
   - Front sts ≈ back sts / 2, rounded to nearest 10n + 11 (using the same formula but fewer repeats)
   - XS front: ~46 sts. 46 - 4 = 42 center sts. 10(3)+7 = 37... 10(4)+7=47... 
   
   This is getting messy. Let me just use the butterfly stitch without requiring fronts to be exact multiples — I'll center the pattern and add/remove edge stitches as needed. Or better yet, I'll plan the fronts to have a set number of butterfly repeats and just note partial patterns at edges.

   **FINAL DECISION**: I'll simplify further for beginner level. The butterfly stitch will be worked as a panel in the CENTER of each piece (back and fronts), with stockinette edges. The panel will be a fixed width (say 3 repeats = 37 sts for the front, and the center of the back uses proportionally more repeats). Seam stitches and edge stitches will be plain stockinette. This way front stitch counts can be anything.

   Actually, even SIMPLER for a beginner: Let me just make the butterfly stitch an ALLOVER pattern, accept that stitch counts are 10n+7 for the body, and work the ribbing over whatever count works, increasing or decreasing at the transition to get to the right count.

   Let me just make clean numbers:
   
   **GAUGE**: 20 sts / 4" = 5 sts per inch

   **Finished Bust (with ~2" ease)**:
   XS: 36", S: 40", M: 44", L: 48", XL: 52"

   Since this is a cardigan worked in pieces:
   - Back width = half the total circumference: 18 (20, 22, 24, 26)"
   - Back sts = 90 (100, 110, 120, 130) sts... but need 10n+7
   
   Let me just use multiples of 10 with the butterfly pattern centered, and the edge 2 sts on each side of back work in stockinette (not part of pattern).

   Back: CO 90 (100, 110, 120, 130) sts
   Edge 2 sts + pattern 86 (96, 106, 116, 126) center sts + edge 2 sts
   86 = 10(7)+7+9 ... nope. 

   I keep running into this. Here's my final final decision:

   **I'll define the butterfly stitch on a multiple of 10 + 2**, which is more flexible. Actually let me look at this differently.

   Standard Butterfly Stitch (my version):
   - Multiple of 10 sts + 2 (for selvage)  
   - I'll define it myself to make it work with my stitch counts.

   OR — and this is what I'll actually do — I'll just use a **butterfly motif** worked as a centered panel, with clear stitch counts that work for each size, and the rest of the body in stockinette. This is actually MORE beginner-friendly because they don't have to worry about maintaining pattern across shaping.

   **FINAL FINAL APPROACH**:
   - Body: Stockinette with a centered butterfly stitch panel
   - The butterfly panel is a fixed 37 sts wide (centered on back, placed on each front)
   - All shaping (armhole, neckline) is done in stockinette sections
   - This is clean, beginner-friendly, and visually appealing

   Actually, you know what, let me just make this TRULY beginner friendly and do an allover butterfly stitch with numbers that work. Let me define a butterfly stitch on multiple of 10 + 7:

   Body stitch counts (10n + 7):
   - XS back: 87 sts = 87/5 = 17.4" → total width = 34.8" (a bit narrow for XS with ease)
   - XS back: 97 sts = 97/5 = 19.4" → total width = 38.8" ✓ (fits size 36" with slight ease)
   
   Let me go with:
   - XS: 97 sts back (= 10×9 + 7), front = 49 sts each
   - S: 107 sts back (= 10×10 + 7), front = 54 sts each  
   - M: 117 sts back (= 10×11 + 7), front = 59 sts each
   - L: 127 sts back (= 10×12 + 7), front = 64 sts each
   - XL: 137 sts back (= 10×13 + 7), front = 69 sts each

   Back widths: 19.4, 21.4, 23.4, 25.4, 27.4"
   Full bust: 38.8, 42.8, 46.8, 50.8, 54.8" — that's too much ease.

   OK I think the issue is I'm trying to make the fronts also exact multiples of the butterfly stitch, which isn't necessary. Let me just say:
   - The back uses full butterfly repeat
   - The fronts use partial butterfly repeat (noting which sts to start on)
   - OR the fronts just use stockinette and only the back has the butterfly

   **TRULY FINAL DECISION**: 
   - Only the BACK has the butterfly stitch pattern (centered panel, 37 sts wide)
   - Fronts are in stockinette with a simple detail
   - This is beginner-friendly, mathematically clean, and looks great

   Wait, re-reading the user request: "butterfly cardigan" — this could also just mean a cardigan with a butterfly motif embroidered on it, OR a "butterfly" style in terms of the shape (open front, flowy). Let me reconsider the name.

   "Butterfly cardigan" in fashion typically refers to:
   1. A draped, open-front style with wide, "wing-like" sleeves or front panels
   2. A cardigan featuring butterfly motifs/decorations
   3. A cardigan worked with butterfly stitch texture

   For beginner level, I think option 2 (simple butterfly motif embroidered as duplicate stitch, or intarsia/simple appliqué) OR option 3 (butterfly stitch texture) makes most sense as a knitting pattern.

   I'll go with **Butterfly Stitch texture** as it's the most authentically knitted approach, and I'll make it work simply.

   **ABSOLUTE FINAL PLAN**:
   
   The butterfly stitch pattern I'll use:
   - Multiple of 10 sts + 7
   - Worked over 12 rows
   - It's a slip-stitch pattern (truly beginner friendly — just knit, purl, and slip)
   
   For stitch counts, I'll work the butterfly pattern across the full body width and adjust cast-on counts accordingly. The ribbing cast-on will be a different (simpler) multiple, and I'll increase/decrease to the butterfly stitch count at the transition.

   Actually the CLEANEST solution: CO in ribbing (multiple of 4), work ribbing, then on the transition row, adjust stitch count to fit butterfly pattern (10n+7). This is totally normal in pattern design and is beginner-friendly.

   **Final Stitch Counts**:
   
   Finished Bust measurements (2" positive ease):
   - XS: 38" | S: 42" | M: 46" | L: 50" | XL: 54"

   For a cardigan: total width = back + 2 fronts (without button overlap, since button bands are picked up)
   Back = half total width, each front = quarter total width (approximately)

   Back sts (at 5 sts/inch):
   - XS: 19" → 95 sts → nearest 10n+7: 97 (19.4") ✓
   - S: 21" → 105 sts → nearest 10n+7: 107 (21.4") ✓
   - M: 23" → 115 sts → nearest 10n+7: 117 (23.4") ✓
   - L: 25" → 125 sts → nearest 10n+7: 127 (25.4") ✓
   - XL: 27" → 135 sts → nearest 10n+7: 137 (27.4") ✓

   Ribbing CO (must be multiple of 4, close to butterfly stitch count):
   - XS: CO 96 sts ribbing, increase 1 st on last rib row = 97 sts ✓
   - S: CO 108 sts ribbing, decrease 1 st on last rib row = 107 sts ✓ (or CO 104, inc 3)
   - M: CO 116 sts ribbing, increase 1 st = 117 sts ✓
   - L: CO 128 sts ribbing, decrease 1 st = 127 sts ✓
   - XL: CO 136 sts ribbing, increase 1 st = 137 sts ✓

   Hmm, odd increases are messy. Let me reconsider.

   Alternative: Just use a butterfly stitch pattern on a multiple of 10, which is much cleaner:
   - Multiple of 10 sts
   - XS: 90 sts (18" back), S: 100 (20"), M: 110 (22"), L: 120 (24"), XL: 130 (26")
   - Finished bust: 36, 40, 44, 48, 52" ✓ (each front = back/2 = 45, 50, 55, 60, 65 sts)
   - CO for 2×2 rib: 90 (100, 110, 120, 130) — all multiples of 10, which are also multiples of 2 ✓ but NOT multiples of 4 for 2×2 rib. 90/4 = 22.5 ✗

   Multiple of 20 would work for both: 100 (100, 120, 120, 140)... not ideal for sizing.

   OK FINAL FINAL FINAL: I'll use a modified butterfly stitch on a multiple of 4 sts, which aligns perfectly with the 2×2 rib. Here's my custom butterfly stitch:

   **Custom Butterfly Stitch** (multiple of 8 sts + 4):
   Row 1 (RS): K2, *sl4 wyif, k4; rep from * to last 2 sts, k2
   Row 2 (WS): Purl all sts
   Row 3: As Row 1
   Row 4: As Row 2
   Row 5: As Row 1
   Row 6: As Row 2
   Row 7 (Catch row): K4, *insert needle under 3 loose strands and k next st, catching strands behind; k7; rep from * to end
   Row 8: Purl
   Row 9: K6, *sl4 wyif, k4; rep from * to last 6 sts, sl4 wyif, k2 — hmm, this doesn't work cleanly.

   Let me use a simpler and cleaner butterfly stitch on multiple of 10 + 5:

   Actually, I'll just COMMIT to a specific butterfly stitch and make the numbers work:

   **BUTTERFLY STITCH** (multiple of 10 + 5):
   Row 1 (RS): K5, *sl5 wyif, k5; rep from * across
   Row 2 (WS): Purl
   Row 3: K5, *sl5 wyif, k5; rep from * across  
   Row 4: Purl
   Row 5 (Catch row): K7, *knit next st catching the 2 loose strands behind it, k9; rep from * to last 8 sts, knit next st catching strands, k7
   Row 6: Purl
   Repeat rows 1-6.

   For multiple of 10 + 5:
   Back sts: 
   - XS: 85 (10×8+5) = 17" → full bust = 34"... too small
   - XS: 95 (10×9+5) = 19" → full bust = 38" ✓ with 2" ease on 36" bust
   - S: 105 (10×10+5) = 21" → full bust = 42" ✓ 
   - M: 115 (10×11+5) = 23" → full bust = 46" ✓
   - L: 125 (10×12+5) = 25" → full bust = 50" ✓
   - XL: 135 (10×13+5) = 27" → full bust = 54" ✓

   Ribbing CO (needs multiple of 4): 95 is not multiple of 4. 

   Solution: CO in ribbing with slightly different count, then adjust on last ribbing row:
   - XS: CO 96 for rib, dec 1 on last rib row → 95 sts for body ✓
   - S: CO 104 for rib, inc 1 → 105 sts ✓
   - M: CO 116 for rib, dec 1 → 115 sts ✓
   - L: CO 124 for rib, inc 1 → 125 sts ✓
   - XL: CO 136 for rib, dec 1 → 135 sts ✓

   This is workable but the +/- 1 adjustments are a bit messy. Let me reconsider sizes.

   What if I adjust the finished measurements slightly to make everything a multiple of 20 (lcm of 4 and 10+5 series)?

   Wait — multiple of 10+5 means: 5, 15, 25, 35, 45, 55, 65, 75, 85, 95, 105, 115, 125, 135...
   Multiple of 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136...

   Numbers that are both (multiple of 20+5... no): multiples of 10+5 that are also multiples of 4:
   LCM(10,4) = 20... the sequence 10n+5: 15, 25, 35, 45, 55, 65, 75, 85, 95, 105...
   None of these are multiples of 4 (they're all odd... wait: 15=odd, 25=odd, 35=odd... all odd numbers! Because 10n is even, +5 is odd, so 10n+5 is always odd. Odd numbers are NEVER multiples of 4.)

   So it's impossible to have a stitch count that's both a multiple of 4 AND a (10n+5) pattern. This means I MUST have a transition row between ribbing and body pattern. That's fine and common.

   **SIMPLIFICATION**: Let me make the ribbing CO a nice round number close to the body stitch count, and do a simple single increase or decrease on the setup row. Knitters are used to this.

   OR — even cleaner for a beginner — I'll use 2×1 rib (k2, p1, multiple of 3) for the hem and cuffs instead of 2×2. Then CO for 2×1 rib with body count divided by 3.

   OR — simplest of all — just use the butterfly stitch throughout, starting from the CO edge. Use a simple cast-on edge and jump right into the pattern. Many textured cardigans do this.

   **TRULY ABSOLUTE FINAL DECISION**:

   I'll use the simplest possible approach:
   - Cast on for body in a multiple that works for BOTH 2×2 rib AND the butterfly stitch
   - I'll design my butterfly stitch to work on a multiple of 4

   **My Custom Butterfly Stitch (multiple of 4)**:
   Row 1 (RS): K2, *sl2 wyif, k2; rep from * to end
   Row 2 (WS): Purl
   Row 3: K2, *sl2 wyif, k2; rep from * to end  
   Row 4: Purl
   Row 5: K2, *sl2 wyif, k2; rep from * to end
   Row 6 (Catch row, RS): K2, *catch the 3 loose strands by inserting needle under them, then knit next st catching them in back; k1; rep from * to last 2 sts, k2... 

   Hmm, with sl2, the butterfly wings would be quite small. Let me try sl4:

   **Butterfly Stitch (multiple of 8)**:
   Rows 1, 3, 5 (RS): K4, *sl4 wyif, k4; rep from * to end (if total = 8n)
   Rows 2, 4, 6 (WS): Purl
   Row 7 (Catch Row, RS): K4, *insert RH needle under 3 long strands, k1 catching strands behind; k7; rep from * ... 

   Wait, with k4/sl4 the catch point is at stitch 5 (first slipped st). Let me think:
   After 3 slip rows: sts 1-4 = knit, sts 5-8 = slipped with long strands

   Row 7: K4, *k1 catching 3 strands (this is st 5, the first slipped st), k7; rep...
   But k7 brings us to the next group of 4 knit sts... then sl4 again... 

   For the offset version:
   Rows 9, 11, 13 (RS): K8, *sl4 wyif, k4; rep from * to last 8 sts... hmm this doesn't work for all widths.

   OK I need to commit to a tried-and-true butterfly stitch recipe. Let me use the CLASSIC BUTTERFLY STITCH as described in standard knitting references:

   **Classic Butterfly Stitch** (multiple of 10 + 7):
   Row 1 (RS): K2, *p3, k7; rep from *, end p3, k2
   Row 2 (WS): P2, *k3, p7; rep from *, end k3, p2
   Row 3: K2, *sl3 wyib, k7; rep from *, end sl3 wyib, k2 — no that's not it either.

   You know what, I've been overthinking this. Let me just use a well-known, clearly documented butterfly stitch:

   **BUTTERFLY STITCH** (multiple of 10 + 5, worked on RS and WS):
   Setup: The slip-stitch butterfly creates "wings" from gathered strands.
   
   Row 1 (RS): K5, *sl5 wyif, k5; rep from * to end
   Row 2 (WS): P all sts
   Row 3: Rep Row 1
   Row 4: P all sts  
   Row 5: Rep Row 1
   Row 6: P all sts
   Row 7 (Gather Row, RS): K7, *RHN under 3 loose strands, k1 (catching strands), k9; rep from * to last 8 sts, RHN under 3 loose strands, k1 catching strands, k7
   Row 8: P all sts
   Row 9: K10, *sl5 wyif, k5; rep from * to last 10 sts... this requires careful centering.

   I'll just commit to numbers that work and use the rib CO transition. Here is my FINAL plan:

   ---

   **DESIGN APPROACH** (final):

   Construction: Basic cardigan, flat pieces, bottom-up. Butterfly stitch on back and front body sections. Stockinette sleeves (simpler for beginner + contrasts nicely). 2×2 rib on hems and cuffs.

   **Butterfly Stitch Pattern** (multiple of 10 + 5):
   Row 1 (RS): *K5, bring yarn to front, sl5 purlwise, bring yarn to back; rep from * to last 5 sts, k5
   Row 2 (WS): Purl all sts
   Rows 3-4: Rep rows 1-2
   Rows 5-6: Rep rows 1-2 (3 total slip rows)
   Row 7 (RS - Gather/Catch Row): K7, *insert right needle under the 3 loose strands, knit next st drawing it through the strands to secure them, k9; rep from * to last 8 sts, insert needle under 3 loose strands, knit next st catching them, k7
   Row 8 (WS): Purl all sts
   Row 9 (RS): K10, *bring yarn to front, sl5 purlwise, bring yarn to back, k5; rep from * to last 10 sts, bring yarn to front, sl5 purlwise, bring yarn to back, k10
   
   Wait, Row 9 requires 10+5 multiple + the offset... For this to work on a (10n+5) count, the second half of the pattern works as:
   Row 9: K10, *sl5 wyif, k5; rep from * to last 10 sts, k10... but that's 10 + (5+5)n + 10 = 20 + 10n which is a multiple of 10+20... doesn't match my 10n+5 count.

   I think the issue is that row 9 (the offset row) requires a different stitch count to work. That's why the standard butterfly stitch has both the catch in the center of the slipped sts AND the offset works out correctly when you have the right total.

   Let me look at this differently. The standard butterfly stitch works as follows (I'll commit to this version):

   **BUTTERFLY STITCH** (worked on multiple of 10 + 7 sts):
   The pattern is 12 rows.
   Row 1 (RS): K1, *sl5 wyif, k5; rep from * to last 6 sts, sl5 wyif, k1
   Row 2 (WS): Purl
   Row 3: Rep Row 1
   Row 4: Purl
   Row 5: Rep Row 1  
   Row 6: Purl
   Row 7 (Catch Row): K1, *k2, insert RH needle under the 3 long strands, k next st pulling loop through strands (catch made), k2, k5; rep from * to last 6 sts, k2, catch st, k3  
   
   I'm confusing myself. Let me just write out a 10+7 repeat clearly:

   With 17 sts example: k1, sl5wyif, k5, sl5wyif, k1 = 1+5+5+5+1 = 17 ✓ (10×1+7)
   With 27 sts: k1, sl5wyif, k5, sl5wyif, k5, sl5wyif, k1 = 1+5+5+5+5+5+1 = 27 ✓ (10×2+7)

   So Row 1: K1, [sl5 wyif, k5] to last 6 sts, sl5 wyif, k1
   Catch row: K1, [k2, catch+k, k2, k5] to last 6 sts, k2, catch+k, k3... wait:

   With 17 sts, catch positions: 
   - First sl5 group is sts 2-6 (positions 2,3,4,5,6), catch goes at middle = st 4 or 5
   - Second sl5 group is sts 12-16, catch at st 14 or 15
   - k1, k1, k1, catch, k2, k5, k1, k1, catch, k3... hmm

   Let me just write out Row 7 for 17 sts:
   k1 (st1), k1(st2), k1(st3), CATCH(st4 - middle of first slip group), k2(sts5-6 were the last 2 of first slip group but now we're at st... 
   
   Wait, I need to track this more carefully. On Row 7, ALL stitches are knit normally - the slip stitches from rows 1-5 are just sitting on the needle. The "catch" is grabbing the 3 loose strands that hang across the front. The catch happens at the center stitch of each former slip group.

   For sts 2-6 (the first sl5 group on Row 1), the center is st 4.
   So Row 7: k1, k2 (sts 2-3), catch at st 4, k2 (sts 5-6), k5 (sts 7-11), k2 (sts 12-13), catch at st 14, k2 (sts 15-16), k1 (st17)
   = k1, k2, catch, k7, catch, k3? Let me recount:
   st1: k1
   sts 2-3: k2
   st4: catch (insert needle under 3 strands, knit st)
   sts 5-11: k7 (sts 5,6 = last of first group, sts 7-11 = first 5 of second knit5 group)
   sts 12-13: k2
   st14: catch
   sts 15-16: k2
   st17: k1
   = k1, k2, catch, k7, catch, k4... that's 1+2+1+7+1+4 = 16 not 17. Let me recount:
   1+2+1+2 (sts5-6) + 5(sts7-11) + 2(sts12-13) + 1(st14) + 2(sts15-16) + 1(st17) = 1+2+1+2+5+2+1+2+1 = 17 ✓

   So Row 7: K1, k2, catch, k9, catch, k4... let me re-add: k1+k2 = k3, catch, k2+k5+k2 = k9, catch, k2+k1 = k3... total = 3+1+9+1+3 = 17 ✓

   So Row 7 for 10n+7: K3, *catch, k9; rep from * to last 4 sts, catch, k3
   Wait: k3, catch(st4), k9(sts5-13), catch(st14), k3(sts15-17) = 3+1+9+1+3 = 17 ✓ for n=1

   For n=2 (27 sts): k3, catch, k9, catch, k9, catch, k3 = 3+1+9+1+9+1+3 = 27 ✓

   So Row 7: K3, *[insert needle under 3 strands, k1 catching strands]; k9; rep from * to last 4 sts, [insert needle under 3 strands, k1 catching strands], k3 ✓

   Now the offset (second) butterfly pattern starts 5 sts later:
   Row 9 (RS): K6, *sl5 wyif, k5; rep from * to last 11 sts, sl5 wyif, k6
   With 17 sts: k6, sl5wyif, k6 = 6+5+6 = 17... but we need a k5 after the sl5: k6, sl5wyif, k5... that's 16, then we have 1 left over. 

   Hmm, 17 sts: k6, sl5wyif... that leaves 6 sts, which isn't a clean k5+1. So for 10+7, the offset row doesn't work cleanly with 1 repeat.

   For 27 sts (n=2): k6, sl5wyif, k5, sl5wyif, k6 = 6+5+5+5+1 = 22... no wait: 6+5+5+5+6 = 27 ✓ 
   
   So Row 9 for n≥2: K6, *sl5 wyif, k5; rep from * to last 11 sts, sl5 wyif, k6
   For 27: k6 + (sl5+k5) × 1 + sl5 + k6 = 6+5+5+5+6 = 27... wait: k6, sl5wyif, k5, sl5wyif, k6 = 6+5+5+5+6 = 27 ✓

   Row 13 (second catch row): K8, *catch, k9; rep from * to last 9 sts, catch, k8
   For 27: k8, catch(st9), k9(sts10-18), catch(st19), k8(sts20-27)... = 8+1+9+1+8 = 27 ✓

   OK! So the complete pattern is:
   Row 1: K1, [sl5 wyif, k5] to last 6 sts, sl5 wyif, k1
   Rows 2, 4, 6, 8: Purl
   Row 3, 5: Rep Row 1
   Row 7: K3, *catch+k1, k9; rep from * to last 4 sts, catch+k1, k3
   Row 9: K6, [sl5 wyif, k5] to last 11 sts, sl5 wyif, k6
   Rows 10, 12: Purl
   Row 11: Rep Row 9
   Row 13: K8, *catch+k1, k9; rep from * to last 9 sts, catch+k1, k8

   Wait, I need to verify Row 13 catch positions. On Rows 9 & 11, the slip groups start at st7:
   Pattern: k6, [sl5, k5], sl5, k6
   For 27 sts: sts 7-11 = first sl5 group, center = st 9
   sts 17-21 = second sl5 group, center = st 19
   
   Row 13: k8 (sts1-8), catch at st9, k9 (sts10-18), catch at st19, k8 (sts20-27)
   = 8+1+9+1+8 = 27 ✓ 

   Row 13: K8, *catch+k1, k9; rep from * to last 9 sts, catch+k1, k8 ✓

   Then the pattern repeats from Row 1. So the full repeat is 12 rows (Rows 1-12, with Row 13 = Row 1 of next repeat... wait let me number properly):

   12-row repeat:
   Rows 1, 3, 5: K1, [sl5 wyif, k5] to last 6 sts, sl5 wyif, k1
   Rows 2, 4, 6: Purl
   Row 7: K3, *[catch st], k9; rep from * to last 4 sts, [catch st], k3
   Row 8: Purl
   Rows 9, 11: K6, [sl5 wyif, k5] to last 11 sts, sl5 wyif, k6
   Rows 10, 12: Purl
   Row 13 (= Row 1 of next repeat): ... wait, we need a catch row for the second set.

   Actually, I think the standard butterfly is 10 rows or 12 rows total. Let me restructure as a 12-row repeat:

   Rows 1, 3, 5: Slip rows (first position) = K1, *sl5 wyif, k5; rep from * to last 6 sts, sl5 wyif, k1
   Rows 2, 4, 6: Purl
   Row 7: Catch row (first position) = K3, *catch, k9; rep from * to last 4 sts, catch, k3
   Row 8: Purl
   Rows 9, 11: Slip rows (second position) = K6, *sl5 wyif, k5; rep from * to last 11 sts, sl5 wyif, k6
   Rows 10, 12: Purl
   — then back to Row 1 (but need a catch row for the second set before Row 1!)

   So it should be a 14-row repeat:
   Rows 1,3,5: Slip (pos 1), Rows 2,4,6: P
   Row 7: Catch (pos 1), Row 8: P
   Rows 9,11,13: Slip (pos 2), Rows 10,12,14: P
   Row 14: Wait, need catch for pos 2 also...

   14-row repeat:
   Rows 1,3,5: Slip pos1
   Rows 2,4,6: Purl  
   Row 7: Catch pos1
   Row 8: Purl
   Rows 9,11,13: Slip pos2
   Rows 10,12,14: Purl
   — catch pos2 should come after row 13/14, so:

   Actually, if we slip for 3 RS rows, then catch on 4th RS row, then slip for 3 more RS rows (with offset), catch on 4th RS row, the pattern is:
   Rows 1, 3, 5 = slip (3 RS rows)
   Row 7 = catch
   Rows 9, 11, 13 = slip (3 RS rows)  
   Row 15 = catch
   Then repeat from Row 1 (= Row 17...)

   That's a 16-row repeat for 3 slip rows each set. Or use 2 slip rows each for a 12-row repeat:

   **12-ROW BUTTERFLY STITCH REPEAT**:
   Rows 1, 3 (RS): Slip pos1 = K1, *sl5 wyif, k5; rep from * to last 6 sts, sl5 wyif, k1
   Rows 2, 4 (WS): Purl
   Row 5 (RS): Catch pos1 = K3, *catch, k9; rep from * to last 4 sts, catch, k3
   Row 6 (WS): Purl
   Rows 7, 9 (RS): Slip pos2 = K6, *sl5 wyif, k5; rep from * to last 11 sts, sl5 wyif, k6
   Rows 8, 10 (WS): Purl
   Row 11 (RS): Catch pos2 = K8, *catch, k9; rep from * to last 9 sts, catch, k8
   Row 12 (WS): Purl
   Rep rows 1-12.

   This gives a clean 12-row repeat! ✓

   Wait, but with only 2 slip rows (not 3), the strands won't be as long/dramatic. Let me use 3 slip rows for a more visible butterfly effect. That gives a 16-row repeat:

   **16-ROW BUTTERFLY STITCH REPEAT**:
   Rows 1, 3, 5 (RS): Slip pos1
   Rows 2, 4, 6 (WS): Purl
   Row 7 (RS): Catch pos1
   Row 8 (WS): Purl
   Rows 9, 11, 13 (RS): Slip pos2
   Rows 10, 12, 14 (WS): Purl
   Row 15 (RS): Catch pos2
   Row 16 (WS): Purl
   Rep rows 1-16.

   16 rows is fine. Let me go with this.

   **VERIFY WITH 27 STS** (multiple of 10 + 7, n=2):
   Row 1: k1, sl5wyif, k5, sl5wyif, k5, sl5wyif, k1 = 1+5+5+5+5+5+1 = 27 ✓
   Row 7: k3, catch, k9, catch, k3 = 3+1+9+1+3 ... that's only for n=1 (17 sts). For n=2:
   k3, catch, k9, catch, k9, catch, k3 = 3+1+9+1+9+1+3 = 27 ✓ 
   Pattern: K3, *[catch], k9; rep from * to last 4 sts, [catch], k3
   For 27: k3, [catch](st4), k9(sts5-13), [catch](st14), k9(sts15-23), [catch](st24), k3(sts25-27)
   = 3+1+9+1+9+1+3 = 27 ✓

   Wait, but k9 between catches is 9 sts, and we have groups at positions: 4, 14, 24. Differences are 10. ✓
   Row 7: K3, *catch (gathering strands), k9; rep from * to last 4 sts, catch, k3 ✓

   Row 9: k6, sl5wyif, k5, sl5wyif, k6 = 6+5+5+5+6 = 27 ✓ (for n=2)
   For n=3 (37 sts): k6, sl5wyif, k5, sl5wyif, k5, sl5wyif, k6 = 6+5+5+5+5+5+6 = 37 ✓
   
   Row 9: K6, *sl5 wyif, k5; rep from * to last 11 sts, sl5 wyif, k6 ✓

   Row 15 (catch pos2): catch positions are at sts 9, 19, 29... 
   For 27: k8, [catch](st9), k9(sts10-18), [catch](st19), k8(sts20-27)
   = 8+1+9+1+8 = 27 ✓
   Pattern: K8, *catch, k9; rep from * to last 9 sts, catch, k8 ✓

   GREAT! The butterfly stitch pattern works for multiple of 10 + 7. Now let me verify for 37 sts (n=3):
   Row 9 catch: sts slipped start at 7, center of first sl5 group is st 9, next is st 19, next is st 29
   K8, [catch](st9), k9, [catch](st19), k9, [catch](st29), k8 = 8+1+9+1+9+1+8 = 37 ✓

   Now the STITCH COUNTS for all sizes. Using multiple of 10+7:
   - 10(8)+7 = 87, 10(9)+7 = 97, 10(10)+7 = 107, 10(11)+7 = 117, 10(12)+7 = 127, 10(13)+7 = 137, 10(14)+7 = 147

   I need back widths of approximately 18, 20, 22, 24, 26" for finished bust of 36, 40, 44, 48, 52".

   Back widths at 5 sts/inch: 90, 100, 110, 120, 130 ideal sts.
   Nearest (10n+7): 87, 97, 107, 117, 127

   Back widths actual: 87/5=17.4", 97/5=19.4", 107/5=21.4", 117/5=23.4", 127/5=25.4"
   Each front = back/2 = 43.5, 48.5, 53.5, 58.5, 63.5 sts (not whole numbers!)

   Problem: fronts need to be roughly half the back. With odd multiples, this doesn't work cleanly.

   **NEW APPROACH**: The fronts do NOT need to follow the butterfly stitch multiple. The fronts will be in STOCKINETTE with the butterfly stitch only on the back. This is actually a lovely design choice — butterfly texture back, smooth fronts. The fronts can be any stitch count.

   OR: Both back and fronts have butterfly stitch. Each front has its own count. Since fronts are about half the back width, each front can have approximately half the butterfly repeats.

   For n=9 (97 sts back): Each front needs about 48-49 sts. Nearest (10n+7): 47 sts (n=4). 
   So each front = 47 sts = 9.4" → two fronts + back = 9.4+19.4+9.4 = 38.2" ✓ for size S-ish

   Hmm but that makes XS:
   Back = 87 sts (17.4"), front = 37 sts each (7.4"), total = 17.4+7.4+7.4 = 32.2"... 
   Adding 2" for button bands gives 34.2" — which is the size, not a 36" finished size with ease.

   Wait, I think I'm conflating the cardigan opening with the body width. In a cardigan, the button band adds about 1" per side, so:
   Total width = back + left front + right front (without bands)
   Finished width = back + left front + right front + 2 × band width

   With 1.5" button bands each side:
   Back = 17.4" + two fronts = 14.8" (7.4" each) + bands = 3" → total = 35.2"
   With some stretch/ease in the yarn, this could work for a 34" bust (XS).

   This isn't quite working elegantly. Let me just go a different route entirely.

   **REVOLUTIONARY SIMPLIFICATION**: 

   I'll use the butterfly stitch as a PANEL/FEATURE, not allover. The cardigan is primarily in stockinette, and I'll add butterfly stitch panels on the back (centered) and/or body panels. This is actually more appropriate for a beginner-level pattern because:
   1. Less complex pattern maintenance
   2. Easier shaping (can shape in stockinette sections)
   3. Clean stitch counts

   OR: Simplest of all — I'll just describe the butterfly stitch as the MAIN BODY STITCH but make it clear that the EXACT stitch count (10n+7) is achieved by adding edge/selvage stitches to a standard cast-on, so:

   CO 92 (102, 112, 122, 132) sts [multiples of 10+2, close to standard sizes]
   Work 2×2 rib for ribbing
   On last rib row, adjust: k1 rib row, increase 5 (3, 3, 3, 5) sts evenly = 97 (105, 115, 125, 137) sts

   Hmm these aren't all multiples of 10+7: 97✓, 105=10(9)+5 ✗ (would need 107), 115=10(10)+5 ✗ (need 117), 125=10(11)+4 ✗ (need 127), 137✓

   I keep failing. Let me just compute what COs work:
   Multiples of 4 near the target: 96, 100, 108, 120, 128
   After adjustment to reach 10n+7:
   96 → 97 (inc 1) ✓ mult of 10+7
   100 → 107 (inc 7) — too many increases
   100 → 97 (dec 3) — that's decreasing quite a bit
   104 → 107 (inc 3) ✓
   108 → 107 (dec 1) ✓ 
   108 → 117 (inc 9) — too many
   116 → 117 (inc 1) ✓
   124 → 127 (inc 3) ✓
   128 → 127 (dec 1) ✓
   136 → 137 (inc 1) ✓

   So:
   XS: CO 96, inc 1 → 97 sts back
   S: CO 108, dec 1 → 107 sts back
   M: CO 116, inc 1 → 117 sts back
   L: CO 128, dec 1 → 127 sts back
   XL: CO 136, inc 1 → 137 sts back

   These are all reasonable! The adjustments are just ±1 to ±3 stitches spread over the row. Very normal.

   Back widths: 19.4 (21.4, 23.4, 25.4, 27.4)"
   Finished bust: 38.8 (42.8, 46.8, 50.8, 54.8)"... that's with 2× back width

   Wait, for a cardigan: total finished width = back + left front + right front. If each front = ~half back:
   Each front ≈ 48.5 (53.5, 58.5, 63.5, 68.5) sts → nearest (10n+7): 47 (57, 57, 67, 67) sts

   Front widths: 9.4 (11.4, 11.4, 13.4, 13.4)"
   But we need roughly half back: 9.7 (10.7, 11.7, 12.7, 13.7)"
   So approximately: 9.4 ≈ 9.7 ✓, 11.4 vs 10.7 (close), etc.

   Total widths (back + 2 fronts):
   XS: 19.4 + 9.4 + 9.4 = 38.2" 
   S: 21.4 + 11.4 + 11.4 = 44.2"
   M: 23.4 + 11.4 + 11.4 = 46.2"
   L: 25.4 + 13.4 + 13.4 = 52.2"
   XL: 27.4 + 13.4 + 13.4 = 54.2"

   Plus button bands (about 1.25" each side = 2.5" total):
   XS: 38.2 + 2.5 = 40.7" — that's too big for XS (which should be ~36-38")
   
   The issue is my fronts are too wide. Fronts should each be ~¼ of the total width (since back = ½ and two fronts together = ½, minus button band overlap).

   For a cardigan, each front is typically slightly less than half the back width. The center front edges meet (or overlap by about 1"). So:
   Each front width ≈ (total finished bust / 2 - back width) / 2 + 1" overlap
   OR more simply: each front width ≈ back width × 0.5

   With the fronts using butterfly stitch, and using (10n+7) multiple:
   XS front: want ~9.5" = 47.5 sts → 47 sts (10×4+7) = 9.4" ✓
   S front: want ~10.5" = 52.5 sts → 57 sts (10×5+7) = 11.4" ... a bit wide. Or 47 sts = 9.4"
   
   This sizing isn't working well because the butterfly repeat is so large (10 sts = 2") that the size jumps are 2" at a time for the fronts.

   **EXECUTIVE DECISION**: I'm going to work the fronts in STOCKINETTE. The butterfly stitch will be on the back only (and possibly just stockinette on the sleeves and fronts). The "butterfly" design will be: butterfly stitch back, smooth stockinette fronts. This is elegant, simpler for a beginner, and means fronts can be any stitch count.

   Actually no — a better beginner-friendly "butterfly" option: Let me just do **butterfly embroidery/appliqué suggestions** in the finishing, or do the butterfly as a SIMPLE MOTIF using a reduced technique.

   **OR** — what if "butterfly" refers to the silhouette/drape? Like a "butterfly jacket" that's an open-front cocoon-style? That's actually a valid interpretation and would make the construction much simpler!

   I think the most satisfying, beginner-appropriate interpretation is:
   1. Basic stockinette cardigan construction 
   2. With butterfly stitch texture on the back panel only (or body, simplified)
   3. Clean stitch counts throughout

   Let me commit RIGHT NOW to a final, workable design:

   ---

   ## FINAL COMMITTED DESIGN

   **Concept**: "Garden Butterfly" Cardigan
   - Worsted weight, beginner level
   - Basic stockinette construction with butterfly slip-stitch texture on body (back and fronts)
   - Sleeves in stockinette
   - 2×2 rib on all hems and cuffs
   - Simple butterfly stitch on a multiple of 6 + 3 (MUCH simpler than the 10+7 version)

   Wait, I want to try a SIMPLE version of butterfly stitch:
   Multiple of 6 + 3:
   Row 1 (RS): K3, *sl3 wyif, k3; rep from * to end
   Row 2 (WS): P3, *sl3 wyib, p3; rep from * to end  — No, this creates long floats on both sides.

   Actually, simpler:
   Row 1 (RS): K3, *sl3 wyif, k3; rep from * to end
   Row 2 (WS): Purl
   Rows 3-4: Rep 1-2
   Row 5 (Catch): K3, *insert needle under the 2 long strands, knit next st (catching strands), k2, k3; rep...

   Multiple of 6+3: e.g., 3, 9, 15, 21, 27, 33, 39, 45, 51, 57, 63, 69, 75, 81, 87, 93...

   For ribbing (multiple of 4): 
   Numbers that work: Need (6n+3) close to multiples of 4:
   6n+3: 3, 9, 15, 21, 27, 33, 39, 45, 51, 57, 63, 69, 75, 81, 87, 93, 99, 105, 111, 117, 123, 129, 135...
   Multiples of 4: ...84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136...
   
   Numbers in sequence 6n+3 that are also multiples of 4? 
   6n+3 mod 4: when n=0: 3%4=3; n=1: 9%4=1; n=2: 15%4=3; n=3: 21%4=1; alternates between 1 and 3 mod 4. Never 0 mod 4. So again, impossible to be both.

   **ANY simple stitch** on a regular multiple will have this conflict with 2×2 rib (multiple of 4) unless the multiple divides 4. So: multiple of 1 (stockinette), multiple of 2, or multiple of 4 will work with 2×2 rib.

   **FINAL ANSWER TO THIS PROBLEM**: Use a butterfly stitch on a multiple of **4** (or 8, or 12).

   **Butterfly Stitch on Multiple of 8**:
   Row 1 (RS): K4, *sl4 wyif, k4; rep from * to end
   Row 2 (WS): Purl
   Row 3: Rep Row 1
   Row 4: Purl
   Row 5: Rep Row 1 (3 slip rows total)
   Row 6: Purl
   Row 7 (Catch): K6, *insert needle under 3 loose strands and k next st; k7; rep from * to last 2 sts, k2
   — wait, let me verify for 16 sts (2 repeats of 8):
   Row 1: k4, sl4wyif, k4, sl4wyif, k4 = 4+4+4+4 = 16 ✓ 
   No wait: k4, sl4wyif, k4, sl4wyif... = 4+4+4+4 = 16 but I only have 4 at the end which repeats the k4 from the start of next repeat. This would be:
   k4, [sl4wyif, k4] to end
   For 8 sts: k4, sl4wyif (end of row? but that means 8 sts: k4+sl4=8 ✓
   For 16 sts: k4, sl4wyif, k4, sl4wyif = 16 ✓
   
   But this isn't symmetric — the last 4 sts are sl4wyif and hang off the end without being caught in the center of a group. The butterfly catch should be at the center of each slipped group.

   For the catch to work symmetrically, I need the slipped sts to be truly in the middle of knit sts. So the pattern should be:
   K2, [sl4wyif, k4] to last 2 sts, end sl4wyif... no that doesn't end cleanly.
   
   A better multiple-of-8 butterfly:
   K2, *sl4 wyif, k4; rep from * to last 6 sts, sl4 wyif, k2
   This requires: 2 + multiple(8) + 6 = 8n + 8 = multiple of 8 ✓ (or written as 8n, where the edge 2+6=8)
   Wait: 2 + [sl4+k4]×n + sl4 + 2 = 2 + 8n + 4 + 2 = 8n + 8 = 8(n+1) = multiple of 8 ✓

   For 16 sts (n=1): K2, sl4wyif, k4, sl4wyif, k2 = 2+4+4+4+2 = 16 ✓
   For 24 sts (n=2): K2, sl4wyif, k4, sl4wyif, k4, sl4wyif, k2 = 2+4+4+4+4+4+2 = 24 ✓

   Catch row: each sl4 group center is at: sts 4-5 (center of first group at st 4.5, so catch at st5 or st4), sts 12-13, etc.
   For 16 sts: slip groups at sts 3-6 (first) and 11-14 (second)
   Centers: st 4.5 → catch at st4 or st5 (I'll use st5)
   K4, catch (st5), K6, catch (st13), K4? Let me count: 4+1+6+1+4 = 16 ✓ 
   But "K6" between catches: sts 6-11 = 4 remaining of first group + k4 + 2 leading into second group.