id:A116774 - OEIS Search Results

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Number of permutations of length n which avoid the patterns 2143, 2341, 4312; or avoid the patterns 1234, 1432, 3412.

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1, 2, 6, 21, 69, 198, 498, 1121, 2305, 4402, 7910, 13509, 22101, 34854, 53250, 79137, 114785, 162946, 226918, 310613, 418629, 556326, 729906, 946497, 1214241, 1542386, 1941382, 2422981, 3000341, 3688134 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.`
	FORMULA	`G.f.: A(x) = -{x(x^6-5x^5+13x^4-14x^3+13x^2-5x+1)}/{(x-1)^7}` `a(n) = (n^6 - 3n^5 + 10n^4 - 15n^3 + 79n^2 - 72n + 180)/180. - Franklin T. Adams-Watters, Sep 16 2006`
	CROSSREFS	`Sequence in context: A001434 A119098 A116842 this_sequence A116756 A116813 A116765` `Adjacent sequences: A116771 A116772 A116773 this_sequence A116775 A116776 A116777`
	KEYWORD	`nonn,easy`
	AUTHOR	`Lara Pudwell (Lara.Pudwell(AT)valpo.edu), Feb 26 2006`

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

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