OFFSET
0,3
FORMULA
a(n) = 1/(-3)^(n/2) - 4^n * Pochhammer(n/2,n)/n! * hypergeom([1,3*n/2],[n+1],4). - Robert Israel, Jan 28 2019
From Vaclav Kotesovec, Jan 29 2019: (Start)
Recurrence: 3*(n-2)*(n-1)*(65*n - 213)*a(n) = (20995*n^3 - 152844*n^2 + 347783*n - 238614)*a(n-2) + 12*(3*n - 10)*(3*n - 8)*(65*n - 83)*a(n-4).
a(n) ~ 2^(n - 1/2) * 3^((3*n - 1)/2) / (5*sqrt(Pi*n)). (End)
G.f.: -(24*x*cos(arcsin(216*x^2-1)/3))/(sqrt(3-324*x^2)*(2*sin(arcsin(216*x^2-1)/3)-11)). - Vladimir Kruchinin, Oct 27 2021
MAPLE
ogf := n -> (1 - 4*x)^(-n/2)*x/(1 - x):
ser := n -> series(ogf(n), x, 46):
seq(coeff(ser(n), x, n), n=0..21);
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Jan 26 2019
STATUS
approved