OFFSET
3,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 3..575
Wikipedia, Partition of a set
MAPLE
b:= proc(n, m) option remember; `if`(n=0, [1, 0],
add((p->`if`(j<4, [p[1], p[2]+p[1]*x^j], p))(
b(n-1, max(m, j))), j=1..m+1))
end:
a:= n-> coeff(b(n, 0)[2], x, 3):
seq(a(n), n=3..25);
MATHEMATICA
b[n_, m_] := b[n, m] = If[n == 0, {1, 0}, Sum[Function[p, If[j < 4, {p[[1]], p[[2]] + p[[1]]*x^j}, p]][b[n - 1, Max[m, j]]], {j, 1, m + 1}]];
a[n_] := Coefficient[b[n, 0][[2]], x, 3];
Table[a[n], {n, 3, 25}] (* Jean-François Alcover, May 27 2018, translated from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 18 2016
STATUS
approved