Quote:
Originally Posted by petrw1
maybe I'm not understanding this right

I think I misunderstood you!
In that case, you can work it out from first principles.
Fix a positive integer \(k\geq N\).
How many ways are there of throwing \(kN\) times without getting \(N\) heads in a row?
What is the probability of each of those possibilities followed by \(N\) consecutive heads?