Shown with a cast-on count of 3 stitches.  

• Row 1 (RS): [Yo, yo, k1] 3 times (9 sts).
• Rows 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20: Knit.
• Row 3: [Yo, k3] 3 times, yo (13 sts).
• Row 5: [K1, yo, k3tog, yo] 3 times, k1.
• Row 7: K2tog, yo, k1, yo, [k3, yo, k1, yo] twice, k2tog (17 sts).
• Row 9: K1, yo, [k1, yo, k1, yo, k1, yo, k3tog, yo] twice, k1, yo, k1, yo, k1, yo, k1 (25 sts).
• Row 11: K1, yo, [k3, yo, k1, yo] 5 times, k3, yo, k1 (37 sts).
• Rows 13 and 17: K2tog, yo, [k3tog, yo, k3, yo] 5 times, k3tog, yo, k2tog (35 sts).
• Rows 15 and 19: K1, yo, [k3, yo, k3tog, yo] 5 times, k3, yo, k1 (37 sts).
• Row 21: K1, yo, [k3, yo, k1, yo] 8 times, k3, yo, k1 (55 sts).