Old Shale in the round

Pattern
Cast on a multiple of 18 sts.
Round 1: Knit.
Round 2: Knit.
Round 3: *(Knit 2 together ) 3 times, (yarn over, Knit 1) 6 times, (Knit 2 together) 3 times; rep from * to end.
Round 4: Purl.
Rep Rounds 1-4.