Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
sum_{n=k}^{\infty} n binom(n,k)(1/k)^(k)(1-1/k)^(n-k)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random