OFFSET
0,2
EXAMPLE
n=12:mod[12!,4096,]=mod[13!,8192]=3072, gcd[3072,3072]=3072=a(12).
MATHEMATICA
Table[GCD[Mod[w!, 2^w], Mod[(w+1)!, 2^(w+1)]], {w, 1, 50}]
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Labos Elemer, Apr 22 2003
STATUS
approved