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 A139751 #2 Mar 31 2012 14:39:55 %S A139751 2,3,5,7,2,3,5,7,5,7,11,13,11,13,17,17,19,23,5 %N A139751 Primes arising in A139749. %K A139751 base,easy,nonn,less %O A139751 1,1 %A A139751 _Ctibor O. Zizka_, May 19 2008