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.
计算 sum from k=1 to 50 of (2k - 1) 。
计算 sum from k=1 to 50 of (2k - 1) 。
Natural Language
Math Input
Extended Keyboard
