Cast on 4x18 sts = 72 sts.
Knit 5 repeats of pattern.
Heel: Put 2 sts (from needle #1) on needle #2 and 2 sts (from needle #4) on needle #3 = 32 sts on heel-needle.
Knit 2 rows normal, knit 30 rows with slip sts.
Pick up 18 sts + 2 (from needle #1), continue with pattern.
Decrease until 18 sts on needle #1 and #4 again (ending with round 4; continue till round 16).
2x pattern, 1x pattern till round 6.

Christmas socks for my father - he never got a pair of handmade socks.