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 A011783 #19 Mar 07 2025 13:31:37 %S A011783 1,1,2,5,13,34,89,233,610,1597,4181,10946,28657,75025,196418,514229 %N A011783 Duplicate of A001519. %K A011783 dead %O A011783 0,3