A299845 a(n) = hypergeom([-n, n - 1], [1], -4).

1, 1, 25, 425, 7025, 116625, 1951625, 32903225, 558265825, 9522632225, 163160773625, 2806202183625, 48420275891025, 837813745045425, 14531896733426025, 252593595973313625, 4398859688478578625, 76733590756134492225, 1340547988367851940825, 23451231922182584693225

Offset

0,3

Links

Robert Israel, Table of n, a(n) for n = 0..798

Formula

4*n*(n-2)^2*a(n) + 4*(n-1)^2*(n-3)*a(n-2) - 4*(2*n-3)*(9*n^2-27*n+17)*a(n-1) = 0. - Robert Israel, Mar 21 2018

a(n) ~ 2^(-3/2) * 5^(3/4) * phi^(6*n - 3) / sqrt(Pi*n), where phi = A001622 = (1 + sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, Jul 05 2018

a(n) = 4^n*Sum_{k=0..n} (5/4)^k*Gamma(n + 1)*Gamma(n - 1)/(Gamma(k + 1)*Gamma(n - k + 1)^2*Gamma(k - 1)) for n >= 2. - Detlef Meya, May 22 2024

Maple

f:= gfun:-rectoproc({4*n*(n-2)^2*a(n)+4*(n-1)^2*(n-3)*a(n-2)-4*(2*n-3)*(9*n^2-27*n+17)*a(n-1)=0,
a(0)=1, a(1)=1, a(2)=25}, a(n), remember):
map(f, [$0..100]); # Robert Israel, Mar 21 2018

Mathematica

a[n_] := Hypergeometric2F1[-n, n - 1, 1, -4]; Table[a[n], {n, 0, 19}]
a[0]:=1; a[1]:=1; a[n_] := 4^n*Sum[(5/4)^k*(Gamma[n + 1]*Gamma[n - 1])/(Gamma[k + 1]*Gamma[n - k + 1]^2*Gamma[k - 1]), {k, 0, n}]; Flatten[Table[a[n], {n, 0, 19}]] (* Detlef Meya, May 22 2024 *)

Crossrefs

Cf. A299506, A243946, A084769, A243947.

Cf. A300945, A300946.

Sequence in context: A020593 A025951 A021944 * A020499 A226712 A020577

Adjacent sequences: A299842 A299843 A299844 * A299846 A299847 A299848

Keyword

nonn

Author

Peter Luschny, Mar 16 2018

Status

approved