I found the solution by my self, anyway I found the way to do it! just have to realize that
(n-2)[N(n-3)+(n-3)[N(n-4)+(n-4)[...]]]]=N(n-1)
in any case, would it be any way to introduce in mathematica a recurrence formula with a for or do loop?? so in case a large number of products or sums...
Hi I'm trying to solve this famous problem with Mathematica:
"How many ways can a math professor incorrectly address Christmas cards so that no card gets to the originally intended recipient"
I found a recurrence formula but don`t know how to implement it in Mathematica, this is the...