id:A126232 - OEIS Search Results

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a(n) is equal to the number of functions f:{1,2,...,n}->{1,2,...,n} such that Im(f) contains 5 fixed elements.

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120, 2520, 52080, 1164240, 28594440, 771309000, 22746757440, 729419296320, 25295774463960, 943934414262840, 37728367833920400, 1608541146018621360, 72881990543360522280, 3497670707401587171240, 177254235519701336515680 (list; graph; listen)

	OFFSET	`5,1`
	LINKS	`Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets`
	FORMULA	`a(n)=n^n-5(n-1)^n+10(n-2)^n-10(n-3)^n+5(n-4)^n-(n-5)^n.`
	EXAMPLE	`a(10)=771309000.`
	MAPLE	`a(n):n->n^n-5(n-1)^n+10(n-2)^n-10(n-3)^n+5(n-4)^n-(n-5)^n;`
	CROSSREFS	`Cf. A126781, A126780, A126779, A126778.` `Sequence in context: A038745 A032180 A000553 this_sequence A105943 A052721 A060490` `Adjacent sequences: A126229 A126230 A126231 this_sequence A126233 A126234 A126235`
	KEYWORD	`nonn`
	AUTHOR	`Aleksandar M. Janjic and Milan R. Janjic (agnus(AT)blic.net), Mar 08 2007`

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Last modified September 7 15:23 EDT 2008. Contains 143483 sequences.

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