Multiples of 4 + 3 + 2 (edge stitches); i.e.: 2 + 16 + 3 = 21 sts. RS: Slip purlwise with yarn in back. WS: Slip purlwise with yarn in front.
Shown with a cast-on count of 0 stitches.
1 2 3 4 5 Horizontal repeats
1 2 3 4 5 Vertical repeats