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 A111480 #4 Dec 05 2013 19:57:05 %S A111480 211,2113,21137777,2113777799999999999,2113777799999999999111111 %N A111480 Primes pertaining to A111479. %C A111480 The next term is 21137777999999999991111111313...13 where the number of trailing 13's is 617. It has 1259 decimal digits. %Y A111480 Cf. A111471, A111472, A111473, A111474, A111475, A111477, A111478, A111479. %K A111480 base,nonn %O A111480 1,1 %A A111480 _Amarnath Murthy_, Aug 05 2005 %E A111480 Corrected by _Max Alekseyev_, May 21 2009