User blog comment:Tachyonic Encrypter/The Hedera Function/@comment-1782812-20141029194717

How about this? It's a little simpler but makes a bit more sense. I think this is sort of what you were trying to go for anyway?

f(x) = x{1}(x-1){2}(x-2){3}(x-3){4}...{x-4}4{x-3}3{x-2}2{x-1}1

It's kinda like the mixed factorial in reverse?