Pattern Question

Just a quick question… I am knitting a pair of leggings for my grandson. The size I am making is 18 months. I’ve followed the directions and I’ve come to the part where it says “Inc 1 st at each end of the next row, etc….until there are 47(51-65-57)". According to the size I am making I would choose the 65……but, wouldn’t it make sense for the 65 to be a 55?? I was wondering if maybe this was a typo???

I vote for typo.