A026849 a(n) = T(2n,n-3), T given by A026736.

1, 9, 56, 300, 1487, 7041, 32381, 146017, 649395, 2859231, 12494914, 54291912, 234860677, 1012433965, 4352210327, 18666918033, 79916230409, 341615895659, 1458457275715, 6220016154525, 26503542364381, 112847001503099, 480173686483581

Offset

3,2

Comments

Is this the same as A026846 and A026842? - R. J. Mathar, Oct 23 2008

Column k=8 of triangle A236830. - Philippe Deléham, Feb 02 2014

Links

G. C. Greubel, Table of n, a(n) for n = 3..1000

Formula

a(n) = A026842(n) = A026846(n). - Philippe Deléham, Feb 02 2014

G.f.: (x^3*C(x)^8)/(1-x*C(x)^3) where C(x) is the g.f. of A000108. - Philippe Deléham, Feb 02 2014

Mathematica

CoefficientList[Series[(1-Sqrt[1-4*x])^8/(32*x^3*(8*x^2 -(1-Sqrt[1-4*x])^3 )), {x, 0, 30}], x] (* G. C. Greubel, Jul 17 2019 *)

Prog

(PARI) my(x='x+O('x^30)); Vec((1-sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-sqrt(1-4*x))^3 ))) \\ G. C. Greubel, Jul 17 2019
(Magma) R<x>:=PowerSeriesRing(Rationals(), 30); Coefficients(R!( (1-Sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-Sqrt(1-4*x))^3 )) )); // G. C. Greubel, Jul 17 2019
(Sage) a=((1-sqrt(1-4*x))^8/(32*x^3*(8*x^2 -(1-sqrt(1-4*x))^3 ))).series(x, 30).coefficients(x, sparse=False); a[3:] # G. C. Greubel, Jul 17 2019

Crossrefs

Cf. A236830.

Sequence in context: A002055 A026842 A026846 * A026879 A026863 A026890

Adjacent sequences: A026846 A026847 A026848 * A026850 A026851 A026852

Keyword

nonn

Author

Clark Kimberling

Status

approved