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URL: https://oeis.org/A127888

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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).

1

0, 478483200, 6401339808768000, 620429964386047303680000, 265250626231132937174895820800000, 371992180902371387782970387300352000000000

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..6.

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

FORMULA

a(n)=sum((-720)^i*binomial(n,i)*(6*n-6*i)!,i=0..n).

EXAMPLE

a(5)=265250626231132937174895820800000

MAPLE

a:=n->sum((-720)^i*binomial(n, i)*(6*n-6*i)!, i=0..n).

CROSSREFS

Sequence in context: A383695 A383696 A147717 * A072232 A011523 A172535

Adjacent sequences: A127885 A127886 A127887 * A127889 A127890 A127891

KEYWORD

nonn

AUTHOR

Milan Janjic, Apr 09 2007

STATUS

approved