Okay, I think I found it - this one
Row 2 - S1, K3, yo, K5, yo, K2tog, yo, K2 - does add up to 13 sts used, and you'll have 15 sts when you finish the row, but row 4 has a double decrease which gets rid of the extra 2 sts and you end with 13. Row 6 starts with 13 and ends up with 11. Don't worry about the changing st numbers too much, though you might want to put st markers every 13 sts on row 2 to show the repeat. Just know that the numbers will change.