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A118969 2*binomial(5*n+1,n)/(4*n+2). 8
1, 2, 11, 80, 665, 5980, 56637, 556512, 5620485, 57985070, 608462470, 6474009360, 69682358811, 757366074080, 8300675584120, 91634565938880, 1018002755977245, 11372548404732930, 127677890035721025, 1439777493407492640 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A quadrisection of A118968.

If y=x+2*x^3+x^5, the series reversion is x=y -2*y^3 +11*y^5 -80*y^7 +665*y^9 -... - R. J. Mathar, Sep 29 2012

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..100

Karol A. Penson and Karol Zyczkowski, Product of Ginibre matrices: Fuss-Catalan and Raney distribution, arXiv version

FORMULA

a(n) is sum of top row terms in M^n, where M is an infinite square production matrix with the tetrahedral series in each column, as follows:

1, 1, 0, 0, 0, 0,...

4, 1, 1, 0, 0, 0,...

10, 10, 4, 1, 0, 0,...

20, 20, 10, 4, 1, 0,...

35, 35, 20, 10, 4, 1,...

... - Gary W. Adamson, Aug 11 2011

G.f.: hypergeom([1/5, 2/5, 3/5, 4/5],[1/2, 3/4, 5/4],3125*x/256)^2  - Mark van Hoeij, Apr 19 2013

a(n) = 2*binomial(5n+1,n-1)/n for n>0, a(0)=1. [Bruno Berselli, Jan 19 2014]

8*n*(4*n+1)*(2*n+1)*(4*n-1)*a(n) -5*(5*n+1)*(5*n-3)*(5*n-2)*(5*n-1)*a(n-1)=0. - R. J. Mathar, Oct 10 2014

EXAMPLE

a(3) = 80 = sum of top row terms in M^n, = (35 + 35 + 9 + 1)

MATHEMATICA

Table[2*Binomial[5n+1, n]/(4n+2), {n, 0, 20}] (* Harvey P. Dale, Aug 21 2011 *)

PROG

(MAGMA) [2*Binomial(5*n+1, n)/(4*n+2): n in [0..20]]; // Vincenzo Librandi, Aug 12 2011

(PARI) a(n)=2*binomial(5*n+1, n)/(4*n+2); \\ Joerg Arndt, Apr 20 2013

CROSSREFS

Sequence in context: A320095 A099661 A027110 * A181068 A056846 A277500

Adjacent sequences:  A118966 A118967 A118968 * A118970 A118971 A118972

KEYWORD

nonn,easy

AUTHOR

Paul Barry, May 07 2006

STATUS

approved

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Last modified May 19 15:15 EDT 2019. Contains 323395 sequences. (Running on oeis4.)