A204841 - OEIS

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A204841

(2n)! - 2^n*n!.

0, 0, 16, 672, 39936, 3624960, 478955520, 87177646080, 20922779566080, 6402373519933440, 2432902004460748800, 1124000727695858073600, 620448401731277448806400, 403291461126554623829606400, 304888344611712432172380979200, 265252859812191015786434789376000 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,3`
	COMMENTS	`a(n) is the number of ways to seat (linearly order) n married couples so that at least one couple is separated.`
	LINKS	`Table of n, a(n) for n=0..15.`
	FORMULA	`a(n) = A010050(n) - A000165(n).`
	MATHEMATICA	`Table[(2n)! - 2^n n!, {n, 0, 20}]`
	CROSSREFS	`Cf. A007060.` `Sequence in context: A222916 A197407 A197429 * A014733 A053907 A222139` `Adjacent sequences: A204838 A204839 A204840 * A204842 A204843 A204844`
	KEYWORD	`nonn`
	AUTHOR	`Geoffrey Critzer, Jan 19 2012`
	STATUS	`approved`

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Last modified June 19 19:26 EDT 2013. Contains 226416 sequences.