OFFSET
1,2
COMMENTS
Also k such that k divides A007429(k).
Also k such that k divides A211780(k). - Jaroslav Krizek, Sep 28 2014
a(28) > 10^10. - Giovanni Resta, Jun 10 2013
a(33) > 5*10^10. - Hiroaki Yamanouchi, Oct 05 2014
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..32
Hiroaki Yamanouchi, Conjectured table of n, a(n) for n = 1..200
MATHEMATICA
t = {}; n = 0; While[n++ <= 20000000, If[Mod[Total[DivisorSigma[1, Divisors[n]]], n] == 0, AppendTo[t, n]]]; t (* Jayanta Basu, Apr 03 2013 *)
PROG
(PARI) for(n=1, 20000000, if(denominator( sumdiv(n, d, numdiv(d)/d)) ==1, print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Apr 06 2002
EXTENSIONS
More terms from Rick L. Shepherd, Jun 23 2002
a(12)-a(27) from Giovanni Resta, Jun 10 2013
a(28) from Hiroaki Yamanouchi, Oct 05 2014
STATUS
approved