sum of G * k * ( (N-G)! * (N-k-1)! ) / ( (N-G-k)! * N! ) from k = 0 to (N-G)

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.