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.
1,2,6,20,70,252,924,3432,12870,48620,184756,705432,2704156,10400600,40116600,155117520
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
