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 A004644 #10 Jun 01 2025 22:42:07 %S A004644 1,2,4,13,31,112,224,1003,2011,4022,13044,31143,112341,230232,1011014 %N A004644 Duplicate of A000866. %K A004644 dead %O A004644 0,2