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 A255204 #8 Mar 07 2015 15:33:05 %S A255204 29,37,43,59,79,97,103,109,113,137,151,181,191,197,199,223,233,241, %T A255204 257,263,281,283,293,307,373,379,397,401,419,421,433,439,449,461,499, %U A255204 521,523,547,557,563,577,601,617,619,641,659,661,701,727,739,743,761,769 %N A255204 Primes p for which exactly one base b with 1 < b < p exists such that p is a base b Wieferich prime. %C A255204 p = prime(n) such that A242830(n) = 1. %o A255204 (PARI) forprime(p=1, , b=2; i=0; while(b < p, if(Mod(b, p^2)^(p-1)==1, i++); b++); if(i==1, print1(p, ", "))) %Y A255204 Cf. A255203, A255205, A255206, A255207, A255208, A255209, A255210. %K A255204 nonn %O A255204 1,1 %A A255204 _Felix Fröhlich_, Feb 17 2015