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A127016 Expansion of 1/(1+7*x*c(x)), c(x) the g.f. of Catalan numbers A000108. 7
1, -7, 42, -259, 1582, -9702, 59388, -363867, 2228310, -13649650, 83599852, -512063790, 3136339276, -19210260076, 117662192928, -720683271819, 4414176556902, -27036862348986, 165600668448348, -1014304512179994, 6212613590747172, -38052263986931796 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Hankel transform is (-7)^n.
LINKS
FORMULA
a(n) = Sum_{k=0..n} A039599(n,k)*(-8)^k.
G.f.: 2/(9 - 7*sqrt(1-4*x)). - G. C. Greubel, May 31 2019
MAPLE
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
MATHEMATICA
CoefficientList[Series[2/(9-7*Sqrt[1-4*x]), {x, 0, 30}], x] (* G. C. Greubel, May 31 2019 *)
PROG
(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
CROSSREFS
Sequence in context: A252700 A033133 A082035 * A152239 A152240 A221794
KEYWORD
sign
AUTHOR
Philippe Deléham, Mar 21 2007
EXTENSIONS
More terms from Emeric Deutsch, Mar 27 2007
STATUS
approved

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Last modified March 29 05:28 EDT 2024. Contains 371264 sequences. (Running on oeis4.)