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 A255210 #6 Mar 22 2015 19:20:59 %S A255210 103291,491531,534851,804367,997961,1026899,1062427,1457389,1550513, %T A255210 2327629,2602307,3093121,3137257,3181481,3412741,3497381,3720179, %U A255210 3814253,4087301,4234057,4891973,5063087,5131237,5194789,5736611,6253349,6903191,6906469,6945047 %N A255210 Primes p for which exactly seven bases b with 1 < b < p exist such that p is a base-b Wieferich prime. %C A255210 p = prime(n) such that A242830(n) = 7. %H A255210 R. Fischer, <a href="http://www.fermatquotient.com/FermatQuotienten/ErstBasen.txt">Thema: Fermatquotient B^(P-1) == 1 (mod P^2) Fermatquotienten mit extremen Erst-Basen</a> %o A255210 (PARI) forprime(p=1, , b=2; i=0; while(b < p, if(Mod(b, p^2)^(p-1)==1, i++); b++); if(i==7, print1(p, ", "))) %Y A255210 Cf. A255203, A255204, A255205, A255206, A255207, A255208, A255209. %K A255210 nonn %O A255210 1,1 %A A255210 _Felix Fröhlich_, Mar 07 2015