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Search: id:A027760
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| A027760 |
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Denominator of Sum 1/p; p-1 | n. |
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+0
13
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| 2, 6, 2, 30, 2, 42, 2, 30, 2, 66, 2, 2730, 2, 6, 2, 510, 2, 798, 2, 330, 2, 138, 2, 2730, 2, 6, 2, 870, 2, 14322, 2, 510, 2, 6, 2, 1919190, 2, 6, 2, 13530, 2, 1806, 2, 690, 2, 282, 2, 46410, 2, 66, 2, 1590, 2, 798, 2, 870
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The gcd of integers x^(n+1)-x, for all integers x. - Roger Cuculiere (cuculier(AT)imaginet.fr), Jan 19 2002
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REFERENCES
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S. C. Locke and A. Mandel, Problem E 2901, American Mathematical Monthly 88 (1981), p. 538. Solution in Vol. 90 (1983), pp. 212-213. [From Daniel M. Rosenblum (DMRosenblum(AT)world.oberlin.edu), Jul 31 2008]
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MAPLE
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A027760 := proc(n) local s, p; s := 0 ; p := 2; while p <= n+1 do if n mod (p-1) = 0 then s := s+1/p; fi; p := nextprime(p) ; od: denom(s) ; end: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 12 2008]
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CROSSREFS
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Cf. A027759.
Sequence in context: A125032 A131980 A076743 this_sequence A122018 A005729 A086660
Adjacent sequences: A027757 A027758 A027759 this_sequence A027761 A027762 A027763
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KEYWORD
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nonn,frac
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AUTHOR
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njas
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