

A141643


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


9




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



