OFFSET
0,4
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..617
Wikipedia, Partition of a set
FORMULA
E.g.f.: exp(x+x^3/6+x^9/9!).
MAPLE
a:= proc(n) option remember; `if`(n=0, 1, add(
`if`(j>n, 0, a(n-j)*binomial(n-1, j-1)), j=[1, 3, 9]))
end:
seq(a(n), n=0..30);
MATHEMATICA
a[n_] := a[n] = If[n == 0, 1, Sum[If[j > n, 0, a[n-j]*Binomial[n-1, j-1]], {j, {1, 3, 9}}]];
Table[a[n], {n, 0, 30}] (* Jean-François Alcover, May 17 2018, translated from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 27 2016
STATUS
approved