OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..449
MATHEMATICA
Table[Sum[(n-k)! k! / Floor[k/2]!^2, {k, 0, n}], {n, 0, 22}] (* Stefano Spezia, Nov 13 2021 *)
PROG
(PARI) a(n) = sum(k=0, n, (n - k)!*k!/(k\2)!^2); \\ Michel Marcus, Nov 13 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Nov 13 2021
STATUS
approved