OFFSET
1,2
COMMENTS
Equals the eigensequence of an infinite lower triangular matrix with (1, 3, 6, ...) in the main diagonal and (1, 1, 1, ...) in the subdiagonal; with the rest zeros. - Gary W. Adamson, Apr 13 2009
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..200
N. J. A. Sloane, Transforms
MAPLE
a:= proc(n) option remember; `if`(n<0, 0,
`if`(n=0, 1, n*(n+1)/2 *a(n-1) +a(n-2)))
end:
seq(a(n), n=1..20); # Alois P. Heinz, Aug 06 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 10 2002
STATUS
approved