login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A026846 a(n) = T(2n+1,n+4), T given by A026725. 4
1, 9, 56, 300, 1487, 7041, 32381, 146017, 649395, 2859231, 12494914, 54291912, 234860677, 1012433965, 4352210327, 18666918033, 79916230409, 341615895659, 1458457275715, 6220016154525, 26503542364381, 112847001503099, 480173686483581 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

COMMENTS

This is probably the same as A026842 because A026725 is built in a left-right symmetric Pascal-tree-summation fashion. - R. J. Mathar, May 28 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) = A026849(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

Drop[CoefficientList[Series[(1-Sqrt[1-4*x])^8/(32*x^3*(8*x^2 -(1 - Sqrt[1-4*x])^3 )), {x, 0, 30}], x], 3] (* 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, A026842,  A026846.

Sequence in context: A172065 A002055 A026842 * A026849 A026879 A026863

Adjacent sequences:  A026843 A026844 A026845 * A026847 A026848 A026849

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 16 23:40 EDT 2021. Contains 343051 sequences. (Running on oeis4.)