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 A090558 #5 Jun 02 2025 00:18:59 %S A090558 11,421,31,41,2551,61,71,6481,8191,101 %N A090558 Duplicate of A068704. %K A090558 dead %O A090558 1,1