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 A089498 #10 Mar 07 2025 13:49:27 %S A089498 0,4,20,120,696,4060,23660,137904,803760,4684660,27304196,159140520 %N A089498 Duplicate of A046729. %K A089498 dead %O A089498 0,2