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A127017 Expansion of 1/(1+6*x*c(x)), where c(x) = g.f. for Catalan numbers A000108. 6
1, -6, 30, -156, 798, -4116, 21132, -108792, 559134, -2876772, 14790660, -76080648, 391221516, -2012174664, 10347690072, -53218984176, 273689323038, -1407575396484, 7238848057812, -37228770844776, 191460735261828, -984660836306904, 5063949044206632, -26043244926688656 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Hankel transform is (-6)^n.

LINKS

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

FORMULA

a(n) = Sum_{k=0..n} A039599(n,k)*(-7)^k.

G.f.: 1/(4 - 3*sqrt(1-4*x)). - G. C. Greubel, May 31 2019

MAPLE

c:=(1-sqrt(1-4*x))/2/x: ser:=series(1/(1+6*x*c), x=0, 27): seq(coeff(ser, x, n), n=0..23); # Emeric Deutsch, Mar 23 2007

MATHEMATICA

CoefficientList[Series[1/(4-3*Sqrt[1-4*x]), {x, 0, 30}], x] (* G. C. Greubel, May 31 2019 *)

PROG

(PARI) my(x='x+O('x^30)); Vec(1/(4-3*sqrt(1-4*x))) \\ G. C. Greubel, May 31 2019

(MAGMA) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( 1/(4 - 3*Sqrt(1-4*x)) )); // G. C. Greubel, May 31 2019

(Sage) (1/(4-3*sqrt(1-4*x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, May 31 2019

CROSSREFS

Cf. A000108, A039599.

Sequence in context: A022023 A066534 A126474 * A152223 A152224 A238769

Adjacent sequences:  A127014 A127015 A127016 * A127018 A127019 A127020

KEYWORD

sign

AUTHOR

Philippe Deléham, Mar 21 2007

EXTENSIONS

More terms from Emeric Deutsch, Mar 23 2007

STATUS

approved

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Last modified October 23 22:15 EDT 2019. Contains 328373 sequences. (Running on oeis4.)