Shown with a cast-on count of 7 stitches.  

• Rows 1, 3, 5, and 7 (RS): Purl.
• Row 2: [Kfb] 7 times (14 sts).
• Row 4: [K1, kfb] 7 times (21 sts).
• Row 6: [K2, kfb] 7 times (28 sts).
• Row 8: [K3, kfb] 7 times (35 sts).
• Rows 9, 11, 13, 15, and 17: [P4, k1] 7 times.
• Rows 10, 12, 14, and 16: Knit.
• Row 18: [K1, [k2tog] twice] 7 times (21 sts).
• Row 19: [P2, k1] 7 times.
• Row 20: [K1, k2tog] 7 times (14 sts).