A075132 a(0)=1; for n > 0, a(n)=sum(binomial(n,k)*binomial(n+k,k+1)*binomial(n+k+1,k),k=0..n)/n.

1, 4, 33, 356, 4415, 59690, 855925, 12809620, 198034395, 3140695856, 50845026815, 837207042270, 13982565667915, 236366796137230, 4037392483733629, 69589308151724084, 1209013441314791891

Offset

0,2

Links

Table of n, a(n) for n=0..16.

Formula

Special values of the hypergeometric function 3F2, in Maple notation: a(n)=hypergeom([ n+1, n+2, -n], [1, 2], -1)

Recurrence: 2*n*(n+1)^2*(59*n^2 - 121*n + 48)*a(n) = n*(2301*n^4 - 4719*n^3 + 1411*n^2 + 943*n - 384)*a(n-1) + (n-1)*(295*n^4 - 900*n^3 + 631*n^2 + 170*n - 168)*a(n-2) + (n-3)*(n-2)*(n-1)*(59*n^2 - 3*n - 14)*a(n-3). - Vaclav Kotesovec, Mar 02 2014

a(n) ~ c * r^n/n^2, where r = 1/6*(39 + (61128 - 177*sqrt(177))^(1/3) + (3*(20376 + 59*sqrt(177)))^(1/3)) = 19.62866250831184052... is the root of the equation 2*r^3 - 39*r^2 - 5*r = 1 and c = sqrt(5/3 + (6647924463616 - 1376397312 * sqrt(177))^(1/3) / 11328 + ((55017913 + 11391*sqrt(177))/2)^(1/3) / (12*59^(2/3)))/Pi = 0.7107949125787545435298127032606174925961199835... - Vaclav Kotesovec, Mar 02 2014, updated Mar 17 2024

Maple

p3 := x^3+5*x^2+39*x-2; p4 := x^4+4*x^3+30*x^2-20*x+1;
y := hypergeom([1/12, 5/12], [1], -1728*p3*x^4/p4^3)/p4^(1/4);
a1 := p3/(5*x+8); a2 := (5*x^3+21*x^2-42*x+178)/(5*x+8)^2;
ogf := (a1*y - Int(a2*y, x) + 1/4)/x;
series(ogf, x=0, 20);  # Mark van Hoeij, Apr 05 2013

Mathematica

Table[ HypergeometricPFQ[{n + 1, n + 2, -n}, {1, 2}, -1], {n, 0, 16}] (* Robert G. Wilson v *)

Crossrefs

Cf. A075514, A074635, A074649, A073530.

Sequence in context: A339654 A347749 A362604 * A303919 A364439 A208961

Adjacent sequences: A075129 A075130 A075131 * A075133 A075134 A075135

Keyword

nonn

Author

Karol A. Penson, Sep 04 2002

Status

approved