Shown with a cast-on count of 21 stitches.  

• Row 1 (RS): P2, yo, p1, *sl1-k2tog-psso, p1, yo, p1, yo, p1, repeat from * to last 6 sts, sl1-k2tog-psso, p1, yo, p2.
• Rows 2, 4, and 6: P3, *k3, p3, repeat from *.
• Row 3: K3, *p2tog, yo, p1, k3, repeat from *.
• Row 5: K3, *p1, yo, p2tog, k3, repeat from *.
• Row 7: K1, k2tog, *p1, yo, p1, yo, p1, sl1-k2tog-psso, repeat from * to last 6 sts, p1, yo, p1, yo, p1, ssk, k1.
• Rows 8, 10, and 12: K3, *p3, k3, repeat from *.
• Row 9: P1, yo, p2tog, *k3, p1, yo, p2tog, repeat from *.
• Row 11: P2tog, yo, p1, *k3, p2tog, yo, p1, repeat from *.