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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
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: A333083 A298611 A136784 * A027277 A242798 A239198
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 March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)