Pattern clarification

In Patons Big Book of Big Baby knitted triangle sweater. Pattern formed by 20 rows. I am confused with the sleeve, doing smallest size cast on 39 st, 5th row into pattern I inc st each end then in doll 4th row until there are 49 sts then in every foll 6th row u til there are 51. I calculate I am doing 82 rows then I knit 13 rows ending with same pattnrow as Back to beg of armhole shaping. If I do this my patter is not matching the Back, I appear to have too many rows. Is anyone familiar with this pattern? Am I reading it wrong?

Welcome to KH!
Are you remembering to increase at each end of the row? It should only take 6 increase rows to go from 39 to 51sts (rows 5,9,13,17,21, and then 27)

Thank you very much, I was misinterpreting the instructions. Thank goodness
for Forums like this one :+1: