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 A154917 #24 Nov 20 2018 18:55:47 %S A154917 0,1,1,3,5,11,21,43,85,171,341,683,1365,2731,5461 %N A154917 Duplicate of A001045. %K A154917 dead %O A154917 0,4 %A A154917 _N. J. A. Sloane_, Nov 20 2018