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Search: id:A063986
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| A063986 |
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Numbers n such that n divides Sum_{k=1..n} A051953(k) where A051953(k)=k-Phi(k). Arithmetic mean of first n cototient values is an integer. |
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+0
4
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| 1, 4, 5, 24, 25, 249, 600, 617, 12272, 13763, 21332, 25228, 783665, 15748051, 41846733, 195853251, 2488541984
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The odd terms of A048290 and A063986 are the same. - Jud McCranie (j.mccranie(AT)comcast.net), Jun 26 2005
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EXAMPLE
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n=5: (1+1+2+2+4)/5 = 2
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MATHEMATICA
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s = 0; Do[s = s + n - EulerPhi[n]; If[ IntegerQ[s/n], Print[n]], {n, 1, 10^7} ]
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CROSSREFS
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Cf. A051953, A000010, A002088, A048920, A000217, A050226.
Sequence in context: A091130 A129346 A010302 this_sequence A039583 A042123 A041531
Adjacent sequences: A063983 A063984 A063985 this_sequence A063987 A063988 A063989
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 06 2001
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EXTENSIONS
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More terms from Dean Hickerson, Sep 07, 2001
One more term from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 07 2001
a(16) and a(17) from J. McCranie, Jun 22, 2005.
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