OFFSET
1,2
FORMULA
For n = 2^t * m with odd m, a(n) = 2^(n-m) * \sum_{d|A007733(n)} gcd(m,2^d-1)^{ \sum_{q|d} moebius(d/q) * gcd(m,2^q-1) / d }. - Max Alekseyev, Jun 11 2009
PROG
(PARI) { A117987(n) = my(m, r); m=n\2^valuation(n, 2); r=2^(n-m); fordiv(znorder(Mod(2, m)), d, r *= gcd(m, 2^d-1)^(sumdiv(d, q, moebius(d\q)*gcd(m, 2^q-1) )\d); ); r } /* Max Alekseyev, Jun 11 2009 */
CROSSREFS
KEYWORD
nonn
AUTHOR
John W. Layman, Apr 11 2006
EXTENSIONS
Extended by Max Alekseyev, Jun 11 2009
STATUS
approved