A165537 - OEIS

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A165537

Number of permutations of length n which avoid the patterns 4213 and 2143.

1, 2, 6, 22, 88, 366, 1556, 6720, 29396, 129996, 580276, 2611290 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	REFERENCES	`Kremer, Darla and Shiu, Wai Chee; Finite transition matrices for permutations avoiding pairs of length four patterns. Discrete Math. 268 (2003), 171-183. MR1983276 (2004b:05006). See Table 1.`
	LINKS	`Wikipedia, Permutation classes avoiding two patterns of length 4.`
	EXAMPLE	`There are 22 permutations of length 4 which avoid these two patterns, so a(4)=22.`
	CROSSREFS	`Sequence in context: A165535 A165536 A032351 * A165538 A165539 A109033` `Adjacent sequences: A165534 A165535 A165536 * A165538 A165539 A165540`
	KEYWORD	`nonn,more,changed`
	AUTHOR	`Vince Vatter (vatter(AT)gmail.com), Sep 21 2009`

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Last modified February 18 00:14 EST 2012. Contains 206085 sequences.