Nice question

A nice question from a book I downloaded today..and I have become an addict

Given a circle of n lights, exactly one of which is initially on, it is permitted to change the state of a bulb provided one also changes the state of every dth bulb after it (where d is a a divisor of n strictly less than n), provided that all n/ d bulbs were originally in the same state as one another. For what values of n is it possible to turn all the bulbs on by making a sequence of moves of this kind?

Its not of olympiad level...its an OK question[1]