OFFSET
1,2
LINKS
Jinyuan Wang, Table of n, a(n) for n = 1..132
MATHEMATICA
Select[Range[351], Nest[EulerPhi, #, 4] === DivisorSigma[0, #] &] (* Amiram Eldar, Jun 12 2022 *)
CROSSREFS
KEYWORD
nonn,easy,fini,full
AUTHOR
Benoit Cloitre, Mar 26 2002
STATUS
approved