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.
2* sum ((1/4)^n/n!*( product (1/2-k) , k=0 to n-1 )) , n=0 to 11
2* sum ((1/4)^n/n!*( product (1/2-k) , k=0 to n-1 )) , n=0 to 11
Natural Language
Math Input
Extended Keyboard