OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..590
Wikipedia, Partition of a set
MAPLE
b:= proc(n, k, m, l) option remember; `if`(n<1, 1,
`if`(l-n>k, 0, b(n-1, k, m+1, n))+m*b(n-1, k, m, l))
end:
a:= n-> b(n-1, min(2, n-1), 1, n):
seq(a(n), n=0..30);
MATHEMATICA
b[n_, k_, m_, l_] := b[n, k, m, l] = If[n < 1, 1, If[l - n > k, 0, b[n - 1, k, m + 1, n]] + m*b[n - 1, k, m, l]];
a[n_] := b[n - 1, Min[2, n - 1], 1, n];
Table[a[n], {n, 0, 30}] (* Jean-François Alcover, May 28 2018, from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, May 22 2017
STATUS
approved