id:A116221 - OEIS Search Results

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If X_1,...,X_n is a partition of a 5n-set X into 5-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, 3614400, 1306371456000, 2432274637386240000, 15509750490368582860800000, 265241692266421512138485760000000, 10332925158674345473855915900600320000000 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets`
	FORMULA	`a(n)=sum((-120)^ibinomial(n,i)(5n-5i)!,i=0..n).`
	EXAMPLE	`a(5)=15509750490368582860800000`
	MAPLE	`a:=n->sum((-120)^ibinomial(n, i)(5n-5i)!, i=0..n).`
	CROSSREFS	`Sequence in context: A083624 A107349 A053078 this_sequence A118813 A127229 A068158` `Adjacent sequences: A116218 A116219 A116220 this_sequence A116222 A116223 A116224`
	KEYWORD	`nonn`
	AUTHOR	`Milan R. Janjic (agnus(AT)blic.net), Apr 09 2007`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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