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 A129266 #9 Feb 12 2023 13:40:30 %S A129266 1,3,3,7,5,9,7,15,9,15 %N A129266 Duplicate of A129527. %K A129266 dead %O A129266 1,2