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A126982
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Expansion of 1/(1+3*x*c(x)), c(x) the g.f. of Catalan numbers A000108.
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7
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1, -3, 6, -15, 30, -78, 144, -423, 630, -2490, 1956, -16998, -5844, -142860, -235740, -1475415, -3951450, -17627490, -57571740, -228692610, -810889020, -3098590020, -11377872720, -43011709110, -160518364740, -606261789828
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OFFSET
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0,2
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COMMENTS
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Hankel transform is (-3)^n.
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} A039599(n,k)*(-4)^k.
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MATHEMATICA
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CoefficientList[Series[2/(5-3*Sqrt[1-4*x]), {x, 0, 30}], x] (* G. C. Greubel, May 28 2019 *)
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PROG
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(PARI) my(x='x+O('x^30)); Vec(2/(5-3*sqrt(1-4*x))) \\ G. C. Greubel, May 28 2019
(Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 2/(5-3*Sqrt(1-4*x)) )); // G. C. Greubel, May 28 2019
(Sage) (2/(5-3*sqrt(1-4*x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 28 2019
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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