Cast on:
Multiple of 4+3 stitches and repeat of 12 rows.

Instruction:
Work one row on purl stitch for having better edge.
Row 1: K2, rep*(Sl3, K1)*, K1
Row 2, 4, 6, 8, 10, 12: Purl stitches
Row 3 (repaet row 1): K2, rep*(Sl3, K1)*, K1
Row 5: K3, rep*(K3tog with strands, K3)*
Row 7: K3, rep*(K1, Sl3)*, K4
Row 9 (repeat row 7) : K3, rep*(K1, Sl3)*, K4
Row 11: K2, rep*(K3, K3tog with strands)*, K2

Note:
K3tog with strands: insert the tip of the right needle from below under the two strands, then pull and put them on the left needle, then knit them with the next knit stitch.