We all know the greek letter delta is the mathematical symbol that represents "change in." I though about a new form of delta: Δn. Where n2 = the # of terms when you expand the delta operator. For example: the usual Δx = x2 - x1 But now: Δ2x = (X4-X3) - (X2-X1). We can see that for Δ2 there are 22 (4) terms. Why the heck haven't I head of this notation. Does it just not exist? It does not seem to be used that much in mathematics. Taking a Δn is like taking the nth derivative of a function is it not? Wow. I discovered something by myself and I didn't even know it existed. Look here: http://en.wikipedia.org/wiki/Difference_operator Scroll down untill you get to the title called "nth difference"