OFFSET
0,3
COMMENTS
Also the number of 7-level rooted trees with n leaves. All n leaves are in level 7.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
B. A. Huberman and T. Hogg, Complexity and adaptation, Evolution, games and learning (Los Alamos, N.M., 1985). Phys. D 22 (1986), no. 1-3, 376-384.
FORMULA
G.f.: Product_{j>0} 1/(1-x^j)^A290355(j).
MAPLE
with(numtheory):
b:= proc(n, k) option remember; `if`(n<2, 1, `if`(k=0, 0, add(
add(b(d, k-1)*d, d=divisors(j))*b(n-j, k), j=1..n)/n))
end:
a:= n-> b(n, 7):
seq(a(n), n=0..30);
MATHEMATICA
b[n_, k_]:=b[n, k]=If[n<2, 1, If[k==0, 0, Sum[Sum[b[d, k - 1]*d, {d, Divisors[j]}] b[n - j, k], {j, n}]/n]]; Table[b[n, 7], {n, 0, 30}] (* Indranil Ghosh, Jul 30 2017, after Maple code *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 28 2017
STATUS
approved