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=1 to infinity \frac{(-1)^{n+1}}{2^{n-1}(n-1)!}
\sum n=1 to infinity \frac{(-1)^{n+1}}{2^{n-1}(n-1)!}
Natural Language
Math Input
Extended Keyboard