OFFSET
0,3
EXAMPLE
a(5) = 1 *5*3*1 + 2 *4*2 + 3*1 *3*1 + 4*2 *2 + 5*3*1 *1 = 15 + 16 + 9 + 16 + 15 = 71.
MATHEMATICA
Table[ Sum[k!!(n + 1 - k)!!, {k, n}], {n, 25}] (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Nov 03 2005
EXTENSIONS
More terms from Robert G. Wilson v, Nov 04 2005
STATUS
approved