Swatch shows a 20-row pattern (3 pattern reps followed by 2 additional rows: A) *K5, yo, k2tog, ssk, yo, k11, yo, k2tog, ask, yo, k5. (This displaces the extra stitch to the center of 2, 4, or any even-numbered series of the cast on multiple.) B) Purl.
Shown with a cast-on count of 29 stitches.