This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A306909 #13 Apr 09 2019 03:20:10 %S A306909 2,11,1093,3511,20771,534851,1006003,3152573 %N A306909 Primes p such that Omega(p + 1)^(p - 1) == 1 (mod p^2), where Omega is A001222. %C A306909 a(9) > 807795277 if it exists. %C A306909 a(9) > 3.5*10^12 if it exists. - _Giovanni Resta_, Apr 09 2019 %e A306909 A001222(20772) = 5 and 5^(20771-1) == 1 (mod 20771^2), so 20771 is a term of the sequence. %t A306909 Select[Prime@ Range@ 230000, PowerMod[ PrimeOmega[# + 1], #-1, #^2] == 1 &] (* _Giovanni Resta_, Apr 09 2019 *) %o A306909 (PARI) forprime(p=1, , if(Mod(bigomega(p+1), p^2)^(p-1)==1, print1(p, ", "))) %Y A306909 Cf. A001220, A001222, A260377, A267487. %K A306909 nonn,hard,more %O A306909 1,1 %A A306909 _Felix Fröhlich_, Mar 16 2019