Shown with a cast-on count of 7 stitches.  

• Rows 1 and 3 (RS): Knit.
• Row 2: Purl.
• Row 4: P3, k1, p3.
• Row 5: K3, (p1, yo, p1) in next st, k3 (9 sts).
• Row 6: P3, k3, p3.
• Row 7: K3, pfb, p1, pfb, k3 (11 sts).
• Row 8: P3, k5, p3.
• Row 9: K3, pfb, p3, pfb, k3 (13 sts).
• Row 10: P3, k7, p3.
• Row 11: K3, pfb, p5, pfb, k3 (15 sts).
• Row 12: P3, k9, p3.
• Row 13: K3, p2tog, p5, p2tog tbl, k3 (13 sts).