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A134639 Conjectured number of numbers k such that sigma(k)/k = n. 3
6, 36, 65, 245, 516 (list; graph; refs; listen; history; text; internal format)
OFFSET
3,1
COMMENTS
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.
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, 3rd Ed., New York, Springer-Verlag, 2004, Section B2.
LINKS
CROSSREFS
Sequence in context: A207590 A226119 A036148 * A069497 A139249 A070150
KEYWORD
nonn,more
AUTHOR
T. D. Noe, Nov 05 2007
STATUS
approved

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Last modified April 20 02:14 EDT 2024. Contains 371798 sequences. (Running on oeis4.)