OFFSET
0,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
G.f. A(x) satisfies: A(x) = A(x^3/(1 - x)^3) / (1 - x).
E.g.f.: exp(x) * Sum_{n>=0} a(n) * x^(3*n) / (3*n)!.
MATHEMATICA
a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, 3 k] a[k], {k, 0, Floor[n/3]}]; Table[a[n], {n, 0, 33}]
nmax = 33; A[_] = 1; Do[A[x_] = A[x^3/(1 - x)^3]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 26 2022
STATUS
approved