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 A084846 mu(n!+1), where mu is the Moebius function (A008683). 4
 -1, -1, -1, -1, 0, 0, 1, 0, 1, -1, 1, -1, 0, 1, 1, -1, -1, -1, 1, 1, 1, -1, -1, 0, 1, 1, 1, -1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, -1, -1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1 (list; graph; refs; listen; history; text; internal format)
 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 Cf. A008683 (mu(n)), A054990 (bigomega(n!+1)), A066856 (omega(n!+1)), A064237 (n!+1 divisible by a square), A002981 (n!+1 is prime). Sequence in context: A302203 A130657 A185916 * A285498 A285504 A130093 Adjacent sequences:  A084843 A084844 A084845 * A084847 A084848 A084849 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

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Last modified February 27 09:18 EST 2020. Contains 332301 sequences. (Running on oeis4.)