No matter what number of sts you cast on.
Row 1: *K1, P1; repeat from * to end.
Row 2: Purl knitted sts and knit purled sts.
Repeat row 2 as long as you need
Row 1: *K1, P1; repeat from * to end.
Row 2: Purl knitted sts and knit purled sts.
Repeat row 2 as long as you need