OFFSET
3,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 3..586
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, k)-> b(n-1, min(k, n-1), 1, n):
a:= n-> (k-> A(n, k)-A(n, k-1))(3):
seq(a(n), n=3..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_, k_] := b[n - 1, Min[k, n - 1], 1, n];
a[n_] := With[{k = 3}, A[n, k] - A[n, k - 1]];
a /@ Range[3, 30] (* Jean-François Alcover, May 05 2020, after Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 29 2018
STATUS
approved