OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..111 (terms < 3*10^10)
MATHEMATICA
Do[If[DivisorSigma[1, n]+EulerPhi[n]==2(EulerPhi[DivisorSigma[1, n]]+DivisorSigma[1, EulerPhi[n]]), Print[n]], {n, 100000000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Farideh Firoozbakht, Oct 16 2013
STATUS
approved