OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Vaclav Kotesovec, Plot of a(n)/(n*log(n)) for n = 2..100000
FORMULA
Numbers k such that k*Sum_{d|k} 1/A000005(d) is an integer.
MATHEMATICA
Select[Range[500], IntegerQ[# * DivisorSum[#, 1/DivisorSigma[0, #1] &]] &] (* Amiram Eldar, Feb 19 2021 *)
PROG
(PARI) isok(k) = denominator(k*sumdiv(k, d, 1/numdiv(d))) == 1; \\ Michel Marcus, Feb 15 2021
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 09 2002
STATUS
approved