Is there a general method for removing a sum from an expression to produce a closed form?
For example I needed to "unroll" the following expression in a recent programming competition (as $k_1$ and $k_2$ are large) and couldn't do it...
$ \sum_{w=2}^{k_1}\sum_{h=2}^{k_2}(w-1)(h-1) $
Do I miss some discrete math training? By what method would you go about solving this? Is there a common textbook that would cover this?