OFFSET
1,4
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
The 575th balanced number is 2089542 = 2*3*7*13*43*89, so a(575)=6; sigma(2089542)/phi(2089542) = 10.
MATHEMATICA
PrimeNu /@ Select[Range[10^5], Divisible[DivisorSigma[1, #], EulerPhi[#]] &] (* Amiram Eldar, Dec 05 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 06 2002
STATUS
approved