Assume that n numbered pancakes are stacked, and that a spatula can be used to reverse the order of the top k pancakes for 2 <= k <= n. The pancake sorting problem asks how many such "prefix reversals" are sufficient to sort an arbitrary stack.

For example, consider the stack:
(top) 5 3 1 4 2 (bottom)
The Pancake Sorting problem is to get this into
(top) 1 2 3 4 5 (bottom)
Thus...
flip(5) -> (top) 2 4 1 3 5 (bottom)
flip(2) -> (top) 4 2 1 3 5 (bottom)
flip(4) -> (top) 3 1 2 4 5 (bottom)
flip(3) -> (top) 2 1 3 4 5 (bottom)
flip(2) -> (top) 1 2 3 4 5 (bottom)

Voila... now where is the maple syrup?