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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

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Adjacent sequences:  A127013 A127014 A127015 * A127017 A127018 A127019

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 October 23 20:17 EDT 2019. Contains 328373 sequences. (Running on oeis4.)