How to create a similar program

[hopesfall]

I've been using this website to calculate stuff but I want to create my own. How could I create something similar to this:

http://www.wolframalpha.com/input/?i=number+of+partitions+of+7

By "this" i mean the general algorithm, not the website

[hanst99]

From the fact that you ask this question I deduce that you can't.