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 A119962 #14 Apr 25 2020 17:27:51 %S A119962 3,7,13,31,61,127,251,509,1021,2039,4093,8191,16381,32749 %N A119962 Duplicate of A014234. %K A119962 dead %O A119962 2,1