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Search: id:A050472
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| A050472 |
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Numbers n such that 2*phi(n) = phi(n+1). |
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+0
5
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| 2, 4, 16, 154, 256, 286, 364, 804, 1066, 2146, 3382, 4550, 6106, 7700, 8176, 9268, 11284, 12556, 12970, 16402, 19228, 19276, 20272, 25132, 26404, 27346, 29154, 29574, 35644, 36418, 38368, 39646, 40494, 47214, 52234, 54652, 65536, 84862
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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R. K. Guy, Unsolved Problems Number Theory, Sect. B36.
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FORMULA
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Conjecture : a(n)/n^3 is bounded. Does lim n -> infinity a(n)/n^3 = 2 ? - Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 07 2002
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EXAMPLE
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phi(256)=128, phi(256+1)=2*128, so 256 is a member of the sequence.
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CROSSREFS
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Cf. A000010, A001274, A050473.
Sequence in context: A009200 A073924 A061588 this_sequence A109457 A105788 A071008
Adjacent sequences: A050469 A050470 A050471 this_sequence A050473 A050474 A050475
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KEYWORD
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nonn
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AUTHOR
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Jud McCranie (j.mccranie(AT)comcast.net), Dec 24 1999
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