OFFSET
1,1
COMMENTS
From Jason Yuen, Jul 01 2024: (Start)
For p>5, an equivalent condition is (240*p*(p-1))^(240*p*(p-1)) == 1 (mod 2821*(1+p+p^2)).
a(9) > 10^12 if it exists. (End)
MATHEMATICA
lastP=2; lst={2}; While[lastP<200, If[
Mod[EulerPhi[900*NextPrime[lastP]^2]^EulerPhi[900*NextPrime[lastP]^2], DivisorSigma[1, 900*NextPrime[lastP]^2]]==1,
AppendTo[lst, NextPrime[lastP]]]; lastP=NextPrime[lastP]]; lst (* Ivan N. Ianakiev, Dec 15 2014 *)
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Farideh Firoozbakht, Dec 12 2014
STATUS
approved