r1: ch 20 and join, hdc in each ch. join with sl st. ch1, turn (20hdc) 
r2: hdc in each hdc, join, ch1, turn. (20hdc) 
r3-6: repeat r2 
r7: hdc in next 10 hdc, 3 hdc in next hdc, hdc in next 9hdc. join, ch1, turn. (22hdc) 
r8: hdc in each hdc. join, ch1, turn. (22hdc) 
r9: hdc in next 9hdc, ch2, sk next 4 hdc, hdc in next 9 hdc. join, ch1, turn. (18hdc, 2ch) 
r10: hdc in next 9 hdc, 2 hdc in ch2 sp, hdc in last 9 hdc. join, ch1, turn. (20hdc) 
r11-r14: repeat r2 but do not turn. 
r15: sc in each hdc around. join. fasten off.