id:A116771 - OEIS Search Results

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Number of permutations of length n which avoid the patterns 1243, 4132, 4321.

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1, 2, 6, 21, 74, 237, 668, 1667, 3750, 7743, 14898, 27033, 46698, 77369, 123672, 191639, 288998, 425499, 613278, 867261, 1205610, 1650213, 2227220, 2967627, 3907910, 5090711, 6565578, 8389761, 10629066, 13358769 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.`
	FORMULA	`G.f.: A(x) = -{(x^9-3x^8+3x^7-4x^6+19x^5-32x^4+27x^3-18x^2+6x-1)x}/{(x-1)^8}` `For n >= 4, a(n) = (5n^6 - 84n^5 + 860n^4 - 5610n^3 + 22535n^2 - 49566n + 45900)/180. - Franklin T. Adams-Watters, Sep 16 2006`
	CROSSREFS	`Sequence in context: A116837 A116781 A047106 this_sequence A116745 A116831 A116752` `Adjacent sequences: A116768 A116769 A116770 this_sequence A116772 A116773 A116774`
	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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