Wave Like Pattern Grasshopper

Hi there,

I am trying to create a wave like pattern using a curve, and then sweep a section along that cruve to create a balustrade post. I wanted to move the z point of the top point of the curve up and down by a fixed increment in a wave like pattern. I have attached my attempt but was getting stuck on how to create a list of numbers that say went from 0 to -150 (in 30 increments) and then repeat once it reachs the limits of that domain.

unnamed.gh (22.1 KB)
Wave Rail.3dm (34.4 KB)