OFFSET
1,1
COMMENTS
This sequence will contain terms of the form 91*P, where P is a perfect number (A000396) not divisible by 7 or 13. Proof: sigma(91*P)/(91*P) = sigma(91)*sigma(P)/(91*P) = 112*(2*P)/(91*P) = 32/13. QED.
LINKS
G. P. Michon, Multiperfect Numbers and Hemiperfect Numbers
Walter Nissen, Abundancy: Some Resources (preliminary version 4)
EXAMPLE
5752422 is a term, since sigma(5752422)/5752422 = 14159808/5752422 = 32/13.
MATHEMATICA
Select[Range[5*10^8], DivisorSigma[1, #]/# == 32/13 &]
Do[If[DivisorSigma[1, k]/k == 32/13, Print[k]], {k, 5*10^8}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Timothy L. Tiffin, Aug 22 2021
EXTENSIONS
a(8)-a(9) from Michel Marcus, Aug 23 2021
STATUS
approved