Shown with a cast-on count of 5 stitches.  

• Row 1 (RS): K2, yo, k1, yo, k2 (7 sts).
• Row 2: K2, p3, k2.
• Row 3: K2, yo, k3, yo, k2 (9 sts).
• Row 4: K2, p5, k2.
• Row 5: K2, yo, k5, yo, k2 (11 sts).
• Row 6: K2, p7, k2.
• Row 7: K2, yo, k7, yo, k2 (13 sts).
• Row 8: K2, p9, k2.
• Row 9: K2, yo, k2tog, k2, yo, k1, yo, k2, ssk, yo, k2 (15 sts).
• Row 10: K2, p11, k2.
• Row 11: K2, yo, k2tog, k2, yo, k3, yo, k2, ssk, yo, k2 (17 sts).
• Row 12: K2, p13, k2.
• Row 13: K2, yo, k2tog, k2, yo, k5, yo, k2, ssk, yo, k2 (19 sts).
• Row 14: K2, p15, k2.
• Row 15: K2, yo, k2, yo, k2, ssk, k3, k2tog, k2, yo, k2, yo, k2 (21 sts).
• Row 16: K2, p17, k2.
• Row 17: K2, yo, k4, yo, k2, ssk, k1, k2tog, k2, yo, k4, yo, k2 (23 sts).
• Row 18: K2, p19, k2.
• Row 19: K2, yo, k6, yo, k2, sl2-k1-p2sso PB, k2, yo, k6, yo, k2 (25 sts).
• Row 20: K2, p21, k2.
• Row 21: K2, yo, k6, k2tog, k2, yo, k1, yo, k2, ssk, k6, yo, k2 (27 sts).