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%I #23 Apr 13 2018 06:36:31
%S 1,1,3,13,67,369,2117,12578,77163,487370,3159905,20970630,142077861,
%T 980386614,6875910589,48927234261,352688735259,2572046483778,
%U 18954720562417,141019525810066,1058260597946701,8004479249101435,60984028315898881,467725424401822465
%N Number of indecomposable permutations avoiding the pattern 2134.
%H Vincenzo Librandi, <a href="/A284717/b284717.txt">Table of n, a(n) for n = 1..200</a>
%H A. L. L. Gao, S. Kitaev, P. B. Zhang. <a href="https://arxiv.org/abs/1605.05490">On pattern avoiding indecomposable permutations</a>, arXiv:1605.05490 [math.CO], 2016. See p. 12.
%F a(n) ~ 3^(2*n+5/2) / (2*Pi*n^4). - _Vaclav Kotesovec_, Apr 02 2017
%t 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 *)
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Apr 02 2017
%E More terms from _Vaclav Kotesovec_, Apr 02 2017
%E Name corrected by _Michael D. Weiner_, Apr 12 2018
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