OFFSET
0,6
FORMULA
a(0) = ... = a(3) = 1; a(n) = Sum_{k=0..n-4} binomial(n-3,k+1) * a(k).
MATHEMATICA
nmax = 31; A[_] = 0; Do[A[x_] = 1 + x + x^2 + x^3 + x^4 A[x/(1 - x)]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[n_] := a[n] = If[n < 4, 1, Sum[Binomial[n - 3, k + 1] a[k], {k, 0, n - 4}]]; Table[a[n], {n, 0, 31}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 16 2022
STATUS
approved