plot [(1, 0), (2, 0.5), (4, 1), (8, 1.5), (16, 2), (32, 2.5), (64, 3), (128, 3.5), (256, 4)]

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.