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 A216437 #12 Sep 08 2012 07:49:29 %S A216437 2,3,5,7,13,19,23,29,31,37,43,47,53,59,61,67,71,79,83,89,97,103,107, %T A216437 109,113,127,131,139,149,151,157,163,167,173,179,181,191,193,197,199, %U A216437 211,223,227,229,233,239,241,263,269,277,281,283,293,307,311,313,317,331 %N A216437 Primes which do not divide any Repunit R(10^n) = (10^(10^n)-1)/9. %C A216437 The primes not in the sequence A178070. %Y A216437 Cf. A178070. %K A216437 nonn %O A216437 1,1 %A A216437 _V. Raman_, Sep 07 2012