A335026 a(n) = (n + 1)^2*a(n - 2) + a(n - 1), starting 0, 9, ....

0, 9, 9, 234, 558, 12024, 47736, 1021680, 5795280, 129418560, 963938880, 22835675520, 211767696000, 5349794688000, 59562324864000, 1605652989696000, 20903846245632000, 600544575525888000, 8962083073778688000, 273802240880695296000, 4611450448589580288000

Offset

1,2

Links

Table of n, a(n) for n=1..21.

Maple

a := proc(n) option remember; if n < 3 then return [0, 9][n] fi;
(n + 1)^2*a(n - 2) + a(n - 1) end: print(seq(a(n), n=1..21));

Crossrefs

Sequence in context: A065242 A050720 A262860 * A353182 A171738 A309316

Adjacent sequences: A335023 A335024 A335025 * A335027 A335028 A335029

Keyword

nonn

Author

Peter Luschny, May 20 2020

Status

approved