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 A323705 #10 May 14 2021 13:48:30 %S A323705 1897121,52368101,126233057 %N A323705 Odd primes p such that ((p+1)/2)^(p-1) == 1 (mod p^2). %C A323705 The corresponding sequence when (p+1) in the congruence is replaced with (p-1) seems to be A125854. %C A323705 a(4) > 4262937421 if it exists. %t A323705 Select[Prime[Range[718*10^4]],PowerMod[(#+1)/2,#-1,#^2]==1&] (* _Harvey P. Dale_, May 14 2021 *) %o A323705 (PARI) forprime(p=3, , my(x=(p+1)/2); if(Mod(x, p^2)^(p-1)==1, print1(p, ", "))) %Y A323705 Cf. A125854, A259502. %K A323705 nonn,hard,bref,more %O A323705 1,1 %A A323705 _Felix Fröhlich_, Jan 24 2019