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 A118320 #21 Oct 10 2019 07:39:03 %S A118320 1,3,2,5,7,6,4,9,11,10,13,15,14,12,8,17,19,18,21,23,22,20,25,27,26,29, %T A118320 31,30,28,24,16,33,35,34,37,39,38,36,41,43,42,45,47,46,44,40,49,51 %N A118320 Duplicate of A108918. %K A118320 dead %O A118320 1,2