OFFSET
1,2
COMMENTS
Although A217389 = a(n)+1 already exists, it is this sequence that one really needs.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..424
MAPLE
b:= proc(n, k) option remember;
`if`(n=0, k!, k*b(n-1, k)+b(n-1, k+1))
end:
a:= proc(n) option remember; `if`(n=0, 0, a(n-1)+b(n, 0)) end:
seq(a(n), n=1..23); # Alois P. Heinz, Feb 20 2025
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
N. J. A. Sloane, Apr 12 2014
STATUS
approved