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

6, 36, 65, 245, 516

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

Table of n, a(n) for n=3..7.

Achim Flammenkamp, The Multiply Perfect Numbers Page

Crossrefs

Sequence in context: A207590 A226119 A036148 * A069497 A139249 A070150

Adjacent sequences: A134636 A134637 A134638 * A134640 A134641 A134642

Keyword

nonn,more

Author

T. D. Noe, Nov 05 2007

Status

approved