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 A046121 #4 May 11 2007 03:00:00 %S A046121 5,11,41,61,251,601,641,1091,1481,1601,1741,1861,2371,2671,3301,3911 %N A046121 Duplicate of A023271. %K A046121 dead %O A046121 1,1