A248862 Primes p such that 900*p^2 is in the sequence A248861.

2, 47, 59, 89, 173, 55439, 561599, 19824479

Offset: 1

Author

Farideh Firoozbakht, Dec 12 2014

Keywords

• nonn
• more
• hard

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)

Crossrefs

Cf. A000040, A248861.

Programs

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 *)