A164871 - OEIS

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A164871

The number of permutations of length n that can be sorted by 3 pop stacks in parallel

1, 2, 6, 24, 118, 644, 3622, 20366, 113686, 630464, 3481084, 19171838, 105444400, 579547826, 3184321642, 17493771830, 96100287256, 527905628552, 2899911094078, 15929870658308, 87506389326742, 480692570563526 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	LINKS	`R. Smith and V. Vatter, The enumeration of permutations sortable by pop stacks in parallel`
	FORMULA	`G.f.: (1-13x+63x^2-148x^3+177x^4-98x^5+18x^6)/(1-14x+75x^2-201x^3+288x^4-\ 216x^5+72x^6)`
	CROSSREFS	`Sequence in context: A097483 A007405 A177518 * A079106 A088713 A193938` `Adjacent sequences: A164868 A164869 A164870 * A164872 A164873 A164874`
	KEYWORD	`nonn`
	AUTHOR	`Vince Vatter (vatter(AT)gmail.com), Aug 29 2009`

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Last modified February 17 14:50 EST 2012. Contains 206050 sequences.