A134639 Conjectured number of numbers k such that sigma(k)/k = n.

6, 36, 65, 245, 516

Offset: 3

Author

T. D. Noe, Nov 05 2007

Keywords

• nonn
• more

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

• Achim Flammenkamp, The Multiply Perfect Numbers Page