VBA: if N matches a numbers in a pattern then do something

Hi bit of a Monday morning puzzle:

I have a series of numbers that always starts at 1 but could be any length. whats the best method for matching numbers that fit my pattern?

The pattern in question is as below (I want to do something on the bold numbers)

1,2,3,4,5,6,7,8,9,10,11,12,13.....

I've got a few ideas but they're all messy/ugly. What I really want is the most elegant way to do solve the problem without manually creating a list of numbers!

Any ideas?

Thanks