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 A012390 #4 Jun 29 2008 03:00:00 %S A012390 2,16,392,21376,1875872,227105536,35750690432,7110343684096 %N A012390 Duplicate of A009613. %K A012390 dead %O A012390 0,1