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A284717 Number of indecomposable permutations avoiding the pattern 2134. 1
1, 1, 3, 13, 67, 369, 2117, 12578, 77163, 487370, 3159905, 20970630, 142077861, 980386614, 6875910589, 48927234261, 352688735259, 2572046483778, 18954720562417, 141019525810066, 1058260597946701, 8004479249101435, 60984028315898881, 467725424401822465 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

A. L. L. Gao, S. Kitaev, P. B. Zhang. On pattern avoiding indecomposable permutations, arXiv:1605.05490 [math.CO], 2016. See p. 12.

FORMULA

a(n) ~ 3^(2*n+5/2) / (2*Pi*n^4). - Vaclav Kotesovec, Apr 02 2017

MATHEMATICA

Rest[CoefficientList[Series[2*x - 1 + x^2/(1-x) + (1-x) * (1 + 5*x - (1-9*x)^(3/4) * (1-x)^(1/4) * HypergeometricPFQ[{-1/4, 3/4}, {1}, 64*x/((x-1)*(1-9*x)^3)])/(6*x^2) - (1 - Sqrt[1-4*x])/2, {x, 0, 30}], x]] (* Vaclav Kotesovec, Apr 02 2017 *)

CROSSREFS

Sequence in context: A201713 A298611 A136784 * A027277 A242798 A239198

Adjacent sequences:  A284714 A284715 A284716 * A284718 A284719 A284720

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 02 2017

EXTENSIONS

More terms from Vaclav Kotesovec, Apr 02 2017

Name corrected by Michael D. Weiner, Apr 12 2018

STATUS

approved

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Last modified October 23 09:24 EDT 2019. Contains 328345 sequences. (Running on oeis4.)