Shown with a cast-on count of 80 stitches.  

• Rows 1 and 3 (RS): K40, k40.
• Row 2: K40, k40.
• Row 4: K18, k2tog, k18, k2tog, ssk, k18, ssk, k18 (76 sts).
• Row 5: K38, k38.
• Row 6: K16, k2tog, k20, k20, ssk, k16 (74 sts).
• Row 7: K34, k2tog, k1, k1, ssk, k34 (72 sts).
• Row 8: K14, k2tog, k16, k2tog, k2, k2, ssk, k16, ssk, k14 (68 sts).
• Row 9: K16, k2tog, k16, k16, ssk, k16 (66 sts).
• Row 10: K12, k2tog, k14, k2tog, k3, k3, ssk, k14, ssk, k12 (62 sts).
• Row 11: K29, kfb, k1, k1, kfb, k29 (64 sts).
• Row 12: K10, k2tog, k3, kfb, k15, kfb, kfb, k15, kfb, k3, ssk, k10 (66 sts).
• Row 13: K13, kfb, k10, k2tog, k7, k7, ssk, k10, kfb, k13.
• Row 14: K8, k2tog, k18, k2tog, k3, k3, ssk, k18, ssk, k8 (62 sts).
• Row 15: K11, kfb, k10, k2tog, k4, k2tog, k1, k1, ssk, k4, ssk, k10, kfb, k11 (60 sts).
• Row 16: K6, k2tog, k4, [k2tog] twice, k8, k2tog, k4, k4, ssk, k8, [ssk] twice, k4, ssk, k6 (52 sts).
• Row 17: K9, kfb, k8, k2tog, k3, kfb, k2, k2, kfb, k3, ssk, k8, kfb, k9 (54 sts).
• Row 18: K4, k2tog, k4, k2tog, k15, k15, ssk, k4, ssk, k4 (50 sts).
• Row 19: K7, kfb, k11, kfb, k5, k5, kfb, k11, kfb, k7 (54 sts).
• Row 20: K2, k2tog, k4, k2tog, k6, k2tog, k1, kfb, k2, k2tog, k3, k3, ssk, k2, kfb, k1, ssk, k6, ssk, k4, ssk, k2 (48 sts).
• Row 21: K5, kfb, k6, k2tog, k10, k10, ssk, k6, kfb, k5.