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A134639
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Conjectured number of numbers k such that sigma(k)/k = n.
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3
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OFFSET
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3,1
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COMMENTS
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These numbers come from Guy and Flammenkamp. Sequences A000396, A005820, A027687, A046060 and A046061 give the k for which the abundancy sigma(k)/k is 2, 3, 4, 5 and 6, respectively. Sequence A054030 gives the abundancy of each multiperfect number A007691.
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REFERENCES
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R. K. Guy, Unsolved Problems in Number Theory, 3rd Ed., New York, Springer-Verlag, 2004, Section B2.
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LINKS
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Table of n, a(n) for n=3..7.
Achim Flammenkamp, The Multiply Perfect Numbers Page
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CROSSREFS
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Sequence in context: A207590 A226119 A036148 * A069497 A139249 A070150
Adjacent sequences: A134636 A134637 A134638 * A134640 A134641 A134642
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KEYWORD
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nonn,more
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AUTHOR
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T. D. Noe, Nov 05 2007
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STATUS
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approved
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