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 A018905 #5 Nov 10 2007 03:00:00 %S A018905 2,4,9,21,50,120,289,697,1682,4060,9801,23661,57122,137904,332929 %N A018905 Duplicate of A024537. %K A018905 dead %O A018905 0,1