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 A253683 #27 Jul 20 2017 23:16:39 %S A253683 71,863,1093,2281,3511,13691,20771,54787,950507,1843757,3188089 %N A253683 Primes p in increasing order with p > A253684(n) > A253685(n) such that (p, A253684(n), A253685(n)) forms a Wieferich triple. %C A253683 In analogy to a Wieferich pair, a set of three primes p, q, r can be called a 'Wieferich triple' if its members satisfy either of the following two sets of congruences: %C A253683 p^(q-1) == 1 (mod q^2), q^(r-1) == 1 (mod r^2), r^(p-1) == 1 (mod p^2) %C A253683 p^(r-1) == 1 (mod r^2), r^(q-1) == 1 (mod q^2), q^(p-1) == 1 (mod p^2) %C A253683 a(9) > 121637. - _Felix Fröhlich_, Jun 18 2016 %C A253683 a(12) > 5*10^6. - _Giovanni Resta_, Jun 20 2016 %H A253683 Wikipedia, <a href="https://en.wikipedia.org/wiki/Wieferich_pair">Wieferich pair</a> %o A253683 (PARI) forprime(p=1, , forprime(q=1, p, forprime(r=1, q, if((Mod(p, q^2)^(q-1)==1 && Mod(q, r^2)^(r-1)==1 && Mod(r, p^2)^(p-1)==1) || (Mod(p, r^2)^(r-1)==1 && Mod(r, q^2)^(q-1)==1 && Mod(q, p^2)^(p-1)==1), print1(p, ", "))))) %Y A253683 Cf. A124121, A124122, A253684, A253685. %K A253683 nonn,hard,more %O A253683 1,1 %A A253683 _Felix Fröhlich_, Jan 09 2015 %E A253683 a(8) from _Felix Fröhlich_, Jun 18 2016 %E A253683 Name edited by _Felix Fröhlich_, Jun 18 2016 %E A253683 a(9)-a(11) from _Giovanni Resta_, Jun 20 2016