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 A216727 #15 Apr 13 2021 16:57:37 %S A216727 1,6,18,93,600,4320,35168,321630,3257109,36199458,438126986,5736774869 %N A216727 Duplicate of A174075. %K A216727 dead %O A216727 3,2