OFFSET
1,2
COMMENTS
See A068977.
1 = 1 , 2 = 1 + 2/tau(2) , 5 = 1 + 2/tau(2) + 3/tau(3) + 6/tau(6) , 7 = 1 + 2/tau(2) + 5/tau(5) + 10/tau(10) ,....
MATHEMATICA
Select[Table[Sum[k/DivisorSigma[0, k], {k, Divisors[n]}], {n, 1, 1000}], IntegerQ[#] &] (* Vaclav Kotesovec, Mar 22 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Naohiro Nomoto, Apr 30 2012
STATUS
approved