Shown with a cast-on count of 2 stitches.  

• Row 1 (RS): Kfb, k1 (3 sts).
• Row 2: Knit to last st, kfb (4 sts).
• Row 3: Kfb, knit (5 sts).
• Row 4: Knit to last st, kfb (6 sts).
• Row 5: Kfb, knit (7 sts).
• Row 6: Knit to last st, kfb (8 sts).
• Row 7: Kfb, knit (9 sts).
• Row 8: Knit to last st, kfb (10 sts).
• Row 9: Kfb, knit (11 sts).
• Row 10: Knit to last st, kfb (12 sts).
• Row 11: Kfb, knit (13 sts).
• Row 12: Knit to last st, kfb (14 sts).
• Row 13: Kfb, knit (15 sts).
• Row 14: Knit to last st, kfb (16 sts).
• Row 15: Kfb, knit (17 sts).
• Row 16: Knit to last st, kfb (18 sts).
• Row 17: Kfb, knit (19 sts).
• Row 18: Knit to last st, kfb (20 sts).
• Row 19: Kfb, *(k1, yo, k1) in next st, sl1 wyib, repeat from * to last st, k1 (39 sts).
• Row 20: K1, *sl1 wyib, k3tog tbl, repeat from * to last 2 sts, sl1 wyib, kfb (22 sts).