id:A082970 - OEIS Search Results

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Number of permutations of length n containing 2 occurrences of 132.

+0
4

4, 23, 107, 464, 1950, 8063, 33033, 134576, 546312, 2212550, 8946454, 36134656, 145831270, 588199815, 2371435125, 9557736480, 38511326040, 155143873170, 624899673690, 2516678580000, 10134353299980, 40805797511622 (list; graph; listen)

	OFFSET	`4,1`
	LINKS	`T. Mansour and A. Vainshtein, Counting occurrences of 132 in a permutation`
	FORMULA	`a(n)=C(2n-6, n-2)(n^3+17n^2-80n+80)/(2n(n-1))`
	PROGRAM	`(PARI) a(n)=binomial(2n-6, n-2)(n^3+17n^2-80n+80)/2/n/(n-1)`
	CROSSREFS	`Sequence in context: A014585 A122738 A038381 this_sequence A017973 A124507 A015532` `Adjacent sequences: A082967 A082968 A082969 this_sequence A082971 A082972 A082973`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 27 2003`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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