id:A127888 - OEIS Search Results

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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).

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0, 478483200, 6401339808768000, 620429964386047303680000, 265250626231132937174895820800000, 371992180902371387782970387300352000000000 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets`
	FORMULA	`a(n)=sum((-720)^ibinomial(n,i)(6n-6i)!,i=0..n).`
	EXAMPLE	`a(5)=265250626231132937174895820800000`
	MAPLE	`a:=n->sum((-720)^ibinomial(n, i)(6n-6i)!, i=0..n).`
	CROSSREFS	`Sequence in context: A038819 A091677 A147717 this_sequence A072232 A011523 A101641` `Adjacent sequences: A127885 A127886 A127887 this_sequence A127889 A127890 A127891`
	KEYWORD	`nonn`
	AUTHOR	`Milan R. Janjic (agnus(AT)blic.net), Apr 09 2007`

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Last modified December 7 08:40 EST 2009. Contains 170430 sequences.

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