Shown with a cast-on count of 51 stitches.  

• Row 1 (RS): *K10, p10, repeat from * to last 11 sts, k10, p1.
• Row 2: P9, *k10, p10, repeat from * to last 2 sts, k2.
• Row 3: K8, *p10, k10, repeat from * to last 3 sts, p3.
• Row 4: P7, *k10, p10, repeat from * to last 4 sts, k4.
• Row 5: K6, *p10, k10, repeat from * to last 5 sts, p5.
• Row 6: P5, *k10, p10, repeat from * to last 6 sts, k6.
• Row 7: K4, *p10, k10, repeat from * to last 7 sts, p7.
• Row 8: P3, *k10, p10, repeat from * to last 8 sts, k8.
• Row 9: K2, *p10, k10, repeat from * to last 9 sts, p9.
• Row 10: P1, *k10, p10, repeat from * to last 10 sts, k10.
• Row 11: *P10, k10, repeat from * to last 11 sts, p10, k1.
• Row 12: K9, *p10, k10, repeat from * to last 2 sts, p2.
• Row 13: P8, *k10, p10, repeat from * to last 3 sts, k3.
• Row 14: K7, *p10, k10, repeat from * to last 4 sts, p4.
• Row 15: P6, *k10, p10, repeat from * to last 5 sts, k5.
• Row 16: K5, *p10, k10, repeat from * to last 6 sts, p6.
• Row 17: P4, *k10, p10, repeat from * to last 7 sts, k7.
• Row 18: K3, *p10, k10, repeat from * to last 8 sts, p8.
• Row 19: P2, *k10, p10, repeat from * to last 9 sts, k9.
• Row 20: K1, *p10, k10, repeat from * to last 10 sts, p10.