id:A116722 - OEIS Search Results

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Number of permutations of length n which avoid the patterns 312, 1324, 3421; or avoid the patterns 312, 1324, 2341, etc.

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1, 2, 5, 12, 25, 47, 82, 135, 212, 320, 467, 662, 915, 1237, 1640, 2137, 2742, 3470, 4337, 5360, 6557, 7947, 9550, 11387, 13480, 15852, 18527, 21530, 24887, 28625, 32772, 37357, 42410, 47962, 54045, 60692, 67937, 75815, 84362, 93615, 103612 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.`
	FORMULA	`G.f.: A(x) = -{x(x^5-3x^3+5x^2-3x+1)}/{(x-1)^5}` `For n >= 2, a(n) = (n^4 - 6n^3 + 47n^2 - 114n + 120)/24. - Franklin T. Adams-Watters, Sep 16 2006`
	CROSSREFS	`Sequence in context: A002836 A116720 A116731 this_sequence A116730 A067331 A116734` `Adjacent sequences: A116719 A116720 A116721 this_sequence A116723 A116724 A116725`
	KEYWORD	`nonn,easy`
	AUTHOR	`Lara Pudwell (Lara.Pudwell(AT)valpo.edu), Feb 26 2006`
	EXTENSIONS	`Extended beyond a(30) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 05 2008`

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

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