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 A121954 #16 Oct 07 2019 14:36:28 %S A121954 0,1,3,13,68,420,3015,24541,223884,2263381,25121075,303716281, %T A121954 3973432728,55931774473,842950049823,13543132571641,231076203767720, %U A121954 4172914800390601 %N A121954 Incorrect duplicate of A058307. %H A121954 <a href="/A121954/b121954.txt">Table of n, a(n) for n = 0..17</a> %K A121954 dead %O A121954 0,3