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.
Sigma(from n = 4 to 2017) 1/(n^2 - 5n + 6)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
