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

+0
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 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`103!+1 = 2743731084943C153, so a(103) is unknown until this 153-digit composite is factored. a(104) = 1 and a(105) = 1. A064237 is the sequence of n such that a(n!+1) = 0.`
	LINKS	`Paul Leyland, Factors of n!+1.`
	EXAMPLE	`a(6)=1 because 6!+1 = 721 = 7 * 103, the product of two different primes, and` `thus mu(6!+1) = (-1)^2 = 1.`
	PROGRAM	`(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: A025447 A131078 A130657 this_sequence A130093 A103368 A055132` `Adjacent sequences: A084843 A084844 A084845 this_sequence A084847 A084848 A084849`
	KEYWORD	`hard,sign`
	AUTHOR	`Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 10 2003`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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