OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
N. J. A. Sloane, Transforms
MAPLE
with(numtheory): dc:= proc(b, c) proc(n) option remember; add(b(d) *c(n/d), d=`if`(n<0, {}, divisors(n))) end end: A:= proc(n, k) local a, b, t; b[1]:= dc(a, a); for t from 2 to k do b[t]:= dc(b[t-1], a) od: a:= n-> `if`(n=1, 1, b[k](n-1)); a(n) end: a:= n-> A(n, 4): seq(a(n), n=1..30);
MATHEMATICA
dc[b_, c_] := Module[{f}, f[n_] := f[n] = Sum[b[d] c[n/d], {d, If[n<0, {}, Divisors[n]]}]; f];
A[n_, k_] := Module[{a, b, t}, b[1] = dc[a, a]; For[t = 2, t <= k, t++, b[t] = dc[b[t-1], a]]; a = Function[m, If[m= 1, 1, b[k][m-1]]]; a[n]];
a[n_] := A[n, 4];
Array[a, 30] (* Jean-François Alcover, Dec 18 2020, after Maple *)
CROSSREFS
KEYWORD
eigen,nonn
AUTHOR
Alois P. Heinz, Sep 21 2008
STATUS
approved