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A284717
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Number of indecomposable permutations avoiding the pattern 2134.
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1
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1, 1, 3, 13, 67, 369, 2117, 12578, 77163, 487370, 3159905, 20970630, 142077861, 980386614, 6875910589, 48927234261, 352688735259, 2572046483778, 18954720562417, 141019525810066, 1058260597946701, 8004479249101435, 60984028315898881, 467725424401822465
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OFFSET
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1,3
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LINKS
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FORMULA
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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