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A038736 T(3*n + 1, n + 1), array T as in A038792. 1
1, 4, 23, 141, 888, 5676, 36622, 237821, 1551727, 10161409, 66732392, 439267525, 2897064773, 19137833146, 126599140313, 838477244705, 5559158604616, 36891869005316, 245025744759152, 1628602268643928, 10832010390274304, 72088640151558145, 480026332241373281, 3198037386794785777, 21315944308822771118 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..24.

FORMULA

G.f.: (g-1)^2/((1-3*g)*(g^2-3*g+1)) where g*(1-g)^2 = x. - Mark van Hoeij, Nov 10 2011

a(n) = A134511(4n,2n). - Alois P. Heinz, Mar 02 2018

a(n) = Sum_{j=0..n} binomial(4*n-j, j). - Petros Hadjicostas, Sep 04 2019

a(n) = hypergeom([1/2 - 2*n, -2*n], [-4*n], -4) - binomial(3*n - 1, n + 1)* hypergeom([1, 1 - n, 3/2 - n], [1 - 3*n, n + 2], -4) for n > 0. - Peter Luschny, Sep 04 2019

a(n) ~ 3^(3*n + 1/2) / (sqrt(Pi*n) * 2^(2*n-1)). - Vaclav Kotesovec, Sep 04 2019

MAPLE

a := n -> `if`(n=0, 1, hypergeom([1/2 - 2*n, -2*n], [-4*n], -4) - binomial(3*n - 1, n + 1)*hypergeom([1, 1 - n, 3/2 - n], [1 - 3*n, n + 2], -4)):

seq(simplify(a(n)), n = 0..24); # Peter Luschny, Sep 04 2019

CROSSREFS

Cf. A038792, A134511.

Sequence in context: A067110 A290052 A158197 * A091642 A162561 A277921

Adjacent sequences:  A038733 A038734 A038735 * A038737 A038738 A038739

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 02 2000

STATUS

approved

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Last modified October 14 16:48 EDT 2019. Contains 328022 sequences. (Running on oeis4.)