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^(k+1) <= ((2^k + 1)(2^(k+1) - 1))/(2^k) < 2^(k+1) + 1
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random