OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[4500], EulerPhi[DivisorSigma[1, #]] == 3*EulerPhi[#] &] (* Amiram Eldar, Apr 23 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 05 2002
STATUS
approved