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 A086219 #3 May 11 2007 03:00:00 %S A086219 0,2,5,11,23,47,95,191,383,767,1535,3071,6143,12287,24575,49151,98303 %N A086219 Duplicate of A055010. %K A086219 dead %O A086219 0,2