OFFSET
0,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..139
Paul Leyland, Factors of n!+1.
Markus Tervooren et al., Factorization of n!+1, FactorDB.
FORMULA
If n is in A064237, then a(n) = 0. Otherwise a(n) = (-1)^A054990(n) = (-1)^A066856(n). - Max Alekseyev, Oct 08 2019
EXAMPLE
a(6)=1 because 6!+1 = 721 = 7 * 103, the product of two different primes and thus mu(6!+1) = (-1)^2 = 1.
PROG
(Magma) [MoebiusMu(Factorial(n)+1) : n in [1..45]];
(PARI) for(n=0, 45, print1(moebius(n!+1), ", "))
CROSSREFS
KEYWORD
hard,sign
AUTHOR
Rick L. Shepherd, Jun 10 2003
EXTENSIONS
a(112) corrected, a(113)-a(114) added by Max Alekseyev, May 28 2015
a(106)-a(107) corrected by Amiram Eldar, Oct 03 2019
STATUS
approved