OFFSET
0,2
COMMENTS
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..500
FORMULA
G.f.: (1/(1 - x)^2) * Sum_{i>=0} x^i / Product_{j=1..i} (1 - j*x). - Ilya Gutkovskiy, Jun 05 2017
MAPLE
b:= proc(n) option remember; `if`(n>0, b(n-1), 0)+combinat[bell](n) end:
a:= proc(n) option remember; `if`(n>0, a(n-1), 0)+b(n) end:
seq(a(n), n=0..30); # Alois P. Heinz, Apr 20 2012
MATHEMATICA
Table[Sum[BellB[k], {k, 0, n }], {n, 0, 24}] // Accumulate (* Jean-François Alcover, Mar 13 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved