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Search: id:A063684
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| A063684 |
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Numbers n such that m(n!) = 2, where m(n) = mu(n) + mu(n+1) + mu(n+2). |
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+0
1
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| 8, 13, 14, 18, 19, 20, 25, 36, 38, 43, 48, 51, 52, 54, 60, 71, 74, 75
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Equivalently, n such that m(n!) = 2, where m(n) = mu(n+1) + mu(n+2), as mu(n!)=0 for all n>=4 (because 4=2^2 divides n!). 87, 91, and 92 are also terms. The only other possible terms with n <= 100 depend upon the factorizations of n!+2 for n=78, 80, 89, 95, 97 and 98. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 20 2003
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LINKS
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Dario A. Alpern, Factorization using the Elliptic Curve Method.
Paul Leyland, Factors of n!+1.
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EXAMPLE
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8! = 40320, mu(40320) = 0, mu(40321) = 1, mu(40322) = 1, which gives 2.
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PROGRAM
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(PARI) m(n) = moebius(n)+moebius(n+1)+moebius(n+2); for(n=1, 10^4, if(m(n!)==2, print(n)))
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CROSSREFS
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Cf. A063838, A008683.
Cf. A084846 (mu(n!+1)).
Adjacent sequences: A063681 A063682 A063683 this_sequence A063685 A063686 A063687
Sequence in context: A124159 A128662 A133192 this_sequence A059194 A080361 A054295
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KEYWORD
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more,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Aug 22 2001
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EXTENSIONS
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More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 20 2003
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