Seed Stitch (even number of stitches):

Row 1 (RS): *Knit 1, purl 1; repeat to end.

Row 2 (WS): *Purl 1, knit 1; repeat to end.

Seed Stitch (odd number of stitches):

Row 1: *Knit 1, purl 1; repeat to last stitch, end k 1. Repeat Row 1.

(Note: Generally when working Seed Stitch, after working the first row one should knit the purl stitches and purl the knit stitches.)