Shown with a cast-on count of 21 stitches.  

• Row 1 (RS): *P1, k2, ssk, yo, p1, yo, k2tog, k2, repeat from * to last st, p1.
• Rows 2, 8, 10, 12, 14, 18, 20, 22, 28, 30, 32, 34, 38, and 40: K1, *p4, k1, repeat from *.
• Row 3: *P1, k1, sl2-k1-p2sso, yo, yo, p1, yo, yo, sl2-k1-p2sso, k1, repeat from * to last st, p1.
• Row 4: K1, *p2, k1, p1, k1, k1, p1, k2, k1, repeat from *.
• Rows 5 and 25: *P1, k2tog, yo, yo, k2tog, repeat from * to last st, p1.
• Rows 6, 16, 26, and 36: K1, *p1, k1, p1, p1, k1, p1, k1, p1, p1, k1, repeat from *.
• Rows 7 and 27: *P1, k4, repeat from * to last st, p1.
• Rows 9 and 29: *P1, ssk, yo, k2, p1, k2, yo, k2tog, repeat from * to last st, p1.
• Row 11: *P1, yo, ssk, k2, p1, k2, k2tog, yo, repeat from * to last st, p1.
• Row 13: *P1, k1, yo, sl1-k2tog-psso, yo, p1, yo, k3tog, yo, k1, repeat from * to last st, p1.
• Row 15: *P1, ssk, yo, yo, ssk, p1, k2tog, yo, yo, k2tog, repeat from * to last st, p1.
• Row 17: *P1, k2, 1/1 RC, p1, 1/1 LC, k2, repeat from * to last st, p1.
• Row 19: *P1, k1, k2tog, yo, k1, p1, k1, yo, ssk, k1, repeat from * to last st, p1.
• Row 21: *P1, yo, k2tog, k2, p1, k2, ssk, yo, repeat from * to last st, p1.
• Row 23: *P1, yo, yo, sl2-k1-p2sso, k1, p1, k1, sl2-k1-p2sso, yo, yo, repeat from * to last st, p1.
• Row 24: K1, *k1, p1, p2, k1, p2, k1, p1, k1, repeat from *.
• Row 31: *P1, k2, k2tog, yo, p1, yo, ssk, k2, repeat from * to last st, p1.
• Row 33: *P1, yo, k3tog, yo, k1, p1, k1, yo, sl1-k2tog-psso, yo, repeat from * to last st, p1.
• Row 35: *P1, k2tog, yo, yo, k2tog, p1, ssk, yo, yo, ssk, repeat from * to last st, p1.
• Row 37: *P1, 1/1 LC, k2, p1, k2, 1/1 RC, repeat from * to last st, p1.
• Row 39: *P1, k1, yo, ssk, k1, p1, k1, k2tog, yo, k1, repeat from * to last st, p1.