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A084846 mu(n!+1), where mu is the Moebius function (A008683). 4

%I

%S -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,

%T 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,

%U 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

%N mu(n!+1), where mu is the Moebius function (A008683).

%H Amiram Eldar, <a href="/A084846/b084846.txt">Table of n, a(n) for n = 0..139</a>

%H Paul Leyland, <a href="http://www.leyland.vispa.com/numth/factorization/factors/factorial+">Factors of n!+1</a>.

%H Markus Tervooren et al., <a href="http://factordb.com/index.php?query=n!%2B1">Factorization of n!+1</a>, FactorDB.

%F If n is in A064237, then a(n) = 0. Otherwise a(n) = (-1)^A054990(n) = (-1)^A066856(n). - _Max Alekseyev_, Oct 08 2019

%e a(6)=1 because 6!+1 = 721 = 7 * 103, the product of two different primes and thus mu(6!+1) = (-1)^2 = 1.

%o (MAGMA) [MoebiusMu(Factorial(n)+1) : n in [1..45]];

%o (PARI) for(n=0,45,print1(moebius(n!+1),","))

%Y Cf. A008683 (mu(n)), A054990 (bigomega(n!+1)), A066856 (omega(n!+1)), A064237 (n!+1 divisible by a square), A002981 (n!+1 is prime).

%K hard,sign

%O 0,1

%A _Rick L. Shepherd_, Jun 10 2003

%E a(112) corrected, a(113)-a(114) added by _Max Alekseyev_, May 28 2015

%E a(106)-a(107) corrected by _Amiram Eldar_, Oct 03 2019

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Last modified April 7 13:55 EDT 2020. Contains 333305 sequences. (Running on oeis4.)