OFFSET
0,6
FORMULA
G.f. A(x) satisfies: A(x) = 1 + x * A(x^4/(1 - x)) / (1 - x).
MATHEMATICA
a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 3 k - 1, k] a[k], {k, 0, Floor[(n - 1)/4]}]; Table[a[n], {n, 0, 46}]
nmax = 46; A[_] = 0; Do[A[x_] = 1 + x A[x^4/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Mar 01 2022
STATUS
approved