A127888 If X_1,...,X_n is a partition of a 6n-set X into 6-blocks then a(n) is equal to the number of permutations f of X such that f(X_i)<>X_i, (i=1,...n).
0, 478483200, 6401339808768000, 620429964386047303680000, 265250626231132937174895820800000, 371992180902371387782970387300352000000000
Offset: 1
Keywords
Examples
a(5)=265250626231132937174895820800000
Links
- Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
Programs
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Maple
a:=n->sum((-720)^i*binomial(n,i)*(6*n-6*i)!,i=0..n).
Formula
a(n)=sum((-720)^i*binomial(n,i)*(6*n-6*i)!,i=0..n).