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 A039947 #1 Dec 11 1999 03:00:00 %S A039947 1,2,3,4,6,7,12,15,20,30,31,60,61,84,105,140,210,211,420,421,422,423, %T A039947 840,841,1260,1261,1540,2310,2520,4620,4621,5460,5461,9240 %N A039947 Erroneous version of A039952. %K A039947 dead %O A039947 1,2