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 j*((n-1)/n)^(j-1) * (1/n) j from 1 to n-1
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random