Shown with a cast-on count of 40 stitches.  

• Rows 1, 3, and 17 (RS): Knit.
• Rows 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20: Purl.
• Row 5: *K8, k2tog, yo, yo, ssk, k8, repeat from *.
• Row 7: *K4, k2tog, yo, k2tog, yo, k4, yo, ssk, yo, ssk, k4, repeat from *.
• Row 9: *K2, k2tog, yo, k12, yo, ssk, k2, repeat from *.
• Row 11: *K1, k2tog, yo, k14, yo, ssk, k1, repeat from *.
• Row 13: *K7, k2tog, yo, k2, yo, ssk, k7, repeat from *.
• Row 15: *Yo, ssk, k1, k2tog, yo, k2tog, yo, k6, yo, ssk, yo, ssk, k1, k2tog, yo, repeat from *.
• Row 19: *K2tog, yo, k16, yo, ssk, repeat from *.