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A127016
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Expansion of 1/(1+7*x*c(x)), c(x) the g.f. of Catalan numbers A000108.
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7
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1, -7, 42, -259, 1582, -9702, 59388, -363867, 2228310, -13649650, 83599852, -512063790, 3136339276, -19210260076, 117662192928, -720683271819, 4414176556902, -27036862348986, 165600668448348, -1014304512179994, 6212613590747172, -38052263986931796
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OFFSET
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0,2
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COMMENTS
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Hankel transform is (-7)^n.
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} A039599(n,k)*(-8)^k.
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MAPLE
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c:=(1-sqrt(1-4*x))/2/x: ser:=series(1/(1+7*x*c), x=0, 25): seq(coeff(ser, x, n), n=0..22); - Emeric Deutsch, Mar 27 2007
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MATHEMATICA
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CoefficientList[Series[2/(9-7*Sqrt[1-4*x]), {x, 0, 30}], x] (* G. C. Greubel, May 31 2019 *)
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PROG
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(PARI) my(x='x+O('x^30)); Vec(2/(9-7*sqrt(1-4*x))) \\ G. C. Greubel, May 31 2019
(Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 2/(9 - 7*Sqrt(1-4*x)) )); // G. C. Greubel, May 31 2019
(Sage) (2/(9-7*sqrt(1-4*x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 31 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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