Cool addendum.

The one calc that used to make my brain hurt is figuring out non-paired offsuit combos. Pairs and suited == easy stuff. But then I finally figured out a shortcut: use spoon's rectangle math above for all combos of non-paired hands and then subtract out the number of suited combos left.

Ex: How many AKo on AcKc9d board? 3 Aces * 3 Kings - 3 suited (d,s,h) = 6
Ex: How many AKo on AcKdKs board? 3 Aces * 2 Kings - 1 suited (h) = 5