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 A212201 #11 Jun 12 2012 11:23:37 %S A212201 1,3,15,85,255,21845,65535,1431655765,4294967295 %N A212201 Records in A212200. %Y A212201 Cf. A212200, A212202, A212203, A212204, A051775. %K A212201 nonn,more %O A212201 1,2 %A A212201 _N. J. A. Sloane_, May 03 2012 %E A212201 a(7)-a(9) from Alex Ryba, Jun 10 2012