Linear Patterns and Equations

I would like to make a linear patterns of holes along thelength of a steel L-Beam. The length of the L-Beam is a changeableparameter, but I can't figure a way to change the number ofrepetitions in the hole-pattern to match. The formula is easy(lengthOfBeam/HoleSpacing) but the pattern dialog will not acceptan equation for the number of reps.

Anybody know of a way to do this?SolidworksParts And Features