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 A139472 #4 Aug 18 2017 16:12:33 %S A139472 1,7,76,732,6732,62934 %N A139472 Incorrect version of A154641 and A154645. %K A139472 dead %O A139472 1,2