Shown with a cast-on count of 40 stitches.  

• Row 1 (RS): *P2, k17, repeat from * to last 2 sts, p2.
• Rows 2, 6, 10, and 14: K2, *p17, k2, repeat from *.
• Row 3: *P2, k5, k2tog, [yo, k1] 3 times, yo, ssk, k5, repeat from * to last 2 sts, p2 (multiple of 21 sts, plus 2).
• Rows 4, 8, and 12: K2, *p19, k2, repeat from *.
• Row 5: *P2, k4, k2tog, k7, ssk, k4, repeat from * to last 2 sts, p2 (multiple of 19 sts, plus 2).
• Row 7: *P2, k3, k2tog, [k1, yo] twice, k3, [yo, k1] twice, ssk, k3, repeat from * to last 2 sts, p2 (multiple of 21 sts, plus 2).
• Row 9: *P2, k2, k2tog, k11, ssk, k2, repeat from * to last 2 sts, p2 (multiple of 19 sts, plus 2).
• Row 11: *P2, k1, k2tog, k2, yo, k1, yo, k5, yo, k1, yo, k2, ssk, k1, repeat from * to last 2 sts, p2 (multiple of 21 sts, plus 2).
• Row 13: *P2, k2tog, k15, ssk, repeat from * to last 2 sts, p2 (multiple of 19 sts, plus 2).
• Repeat rows 3-14.