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 A255921 #16 Dec 06 2020 00:05:45 %S A255921 2,3,4,6,11,12,14,15,16,20,34,36,39,47,52,56,58,59,66,72,83,84,86,87, %T A255921 88,90,92,95,96,102,103,104,106,108,111,114,119,123,135,139,140,142, %U A255921 144,156,159,160,162,167,171,175,180,183,186,187,194,198,200,203,204 %N A255921 Bases b for which no primes p with p < b exist such that p is a base-b Wieferich prime. %C A255921 Numbers b such that A255920(b) = 0. %C A255921 Complement of A273786. - _Felix Fröhlich_, Dec 03 2020 %H A255921 Felix Fröhlich, <a href="/A255921/b255921.txt">Table of n, a(n) for n = 1..10000</a> %o A255921 (PARI) is(b) = forprime(p=1, b-1, if(Mod(b, p^2)^(p-1)==1, return(0))); 1 %Y A255921 Cf. A255920, A255922, A255923, A255924, A255925, A273786. %K A255921 nonn %O A255921 1,1 %A A255921 _Felix Fröhlich_, Mar 11 2015