A141643 Numbers n such that sigma(n)/n = 5/2.

24, 91963648, 10200236032

Offset

1,1

Comments

There are no other terms through 2^34. - Walter Nissen, Apr 17 2009

No more terms below 10^12. - Jud McCranie, Aug 30 2013

Links

Table of n, a(n) for n=1..3.

G. P. Michon, Multiperfect and hemiperfect numbers

Walter Nissen, Abundancy : Some Resources

Walter Nissen, Abundancy : Some Resources

Walter Nissen, Primitive Friendly Pairs with friends < 2^34 with denom < 20000

Mathematica

Select[Range[100000], DivisorSigma[1, #]/# == 5/2 &] (* Robert Price, Apr 03 2019 *)

Prog

(PARI) isok(n) = sigma(n, -1) == 5/2; \\ Michel Marcus, Apr 04 2019

Crossrefs

Cf. A055153, A141645, A159271, A160678.

Sequence in context: A255322 A319900 A172803 * A275026 A297424 A013910

Adjacent sequences: A141640 A141641 A141642 * A141644 A141645 A141646

Keyword

nonn,more,bref

Author

Yasutoshi Kohmoto, May 10 2008

Extensions

Definition rewritten by M. F. Hasler, May 10 2008

First three terms confirmed by Ray Chandler, Sep 18 2008

Status

approved