Animate[Plot3D[Sin[Pi*x/n]*Cos[Pi*y/n], {x, -2, 2}, {y, -2, 2}], {n, 1, 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.