Shown with a cast-on count of 5 stitches.  

• Row 1 (RS): K2, yo, k1, yo, k2 (7 sts).
• Rows 2, 4, 6, 8, 10, 12, 14, 16, and 18: K2, purl to last 2 sts, k2.
• Row 3: K2, yo, k1, yo, k1, yo, k1, yo, k2 (11 sts).
• Row 5: K2, yo, k3, yo, k1, yo, k3, yo, k2 (15 sts).
• Row 7: K2, yo, k1, yo, k3, yo, k1, yo, k1, yo, k1, yo, k3, yo, k1, yo, k2 (23 sts).
• Row 9: K2, *yo, k3, yo, sl1-k2tog-psso, yo, k3, yo, repeat from * to last 12 sts, k1, yo, k3, yo, sl1-k2tog-psso, yo, k3, yo, k2 (27 sts).
• Row 11: K2, [yo, k1] twice, k2tog, [k1, yo] twice, k1, ssk, [k1, yo] twice, k1, [yo, k1] twice, k2tog, [k1, yo] twice, k1, ssk, [k1, yo] twice, k2 (35 sts).
• Row 13: K2, yo, [k3, yo, sl1-k2tog-psso, yo] twice, k3, yo, k1, yo, [k3, yo, sl1-k2tog-psso, yo] twice, k3, yo, k2 (39 sts).
• Row 15: K2, [yo, k1] twice, k2tog, k1, yo, k1, yo, k1, sl1-k2tog-psso, k1, yo, k1, yo, k1, ssk, [k1, yo] twice, k1, [yo, k1] twice, k2tog, k1, yo, k1, yo, k1, sl1-k2tog-psso, k1, yo, k1, yo, k1, ssk, [k1, yo] twice, k2 (47 sts).
• Row 17: K2, yo, k3, [yo, sl1-k2tog-psso, yo, k3] 3 times, yo, k1, yo, k3, [yo, sl1-k2tog-psso, yo, k3] 3 times, yo, k2 (51 sts).