OFFSET
0,2
FORMULA
a(n) = [x^n] 1/((1-x-x^3) * (1-x)^(n+1)).
From Vaclav Kotesovec, Apr 08 2024: (Start)
Recurrence: (n-1)*a(n) = (9*n-11)*a(n-1) - 2*(11*n-16)*a(n-2) + (9*n-13)*a(n-3) - 2*(2*n-3)*a(n-4).
G.f.: 2 / (4*x^2 + 3*x*sqrt(1-4*x) - 9*x + 2).
a(n) ~ 2^(2*n+3) / (3*sqrt(Pi*n)). (End)
PROG
(PARI) a(n) = sum(k=0, n\3, binomial(2*n-2*k+1, n-3*k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 08 2024
STATUS
approved