OFFSET
1,6
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
N. J. A. Sloane, Transforms
FORMULA
G.f.: x + x^2 + x^3 + x^4 * (1 + Sum_{i>=1} Sum_{j>=1} a(i)*a(j)*x^(i*j)). - Ilya Gutkovskiy, May 09 2019
MAPLE
k:= 4: with(numtheory): dck:= proc(b, c) proc(n, k) option remember; add(b(d, k) *c(n/d, k), d=`if`(n<0, {}, divisors(n))) end end: B:= dck(T, T): T:= (n, k)-> if n<=k then 1 else B(n-k, k) fi: a:= n-> T(n, k): seq(a(n), n=1..55);
MATHEMATICA
dck[b_, c_][n_, k_] := dck[b, c][n, k] = Sum[b[d, k]*c[n/d, k], {d, If[n < 0, {}, Divisors[n]]}];
B = dck[T, T];
T[n_, k_] := If[n <= k, 1, B[n - k, k]];
a[n_] := T[n, 4];
Array[a, 55] (* Jean-François Alcover, Jun 11 2018, after Alois P. Heinz *)
CROSSREFS
KEYWORD
eigen,nonn
AUTHOR
Alois P. Heinz, Sep 18 2008
STATUS
approved