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Anyway, the thing I noticed, while doing some calculations on permutations, that for any x>=2, x*(x-1) is always even. This seemed logical enough when I thought about it, because whether n is odd or even, x-1 will be the opposite, and odd*even=even. But the property extends beyond two terms; for x>=3, x*(x-1)*(x-2) is always divisible by 6; adding (x-3) makes it divisible by 24, and so on.

I know logically why these are true, based on how I was coming up with the equations in the first place, but mathematically it seems a bit unusual. If anyone recognizes this and can point me to more info, or just tell me what it's called, I'd be appreciative.