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 A239380 #8 Mar 19 2014 13:08:19
%S A239380 1,1,4,27,255,3028,41966,646404
%N A239380 Words of length n over the alphabet {0,...,n-1} that avoid the pattern 2413.
%Y A239380 Cf. A239295.
%K A239380 nonn,more
%O A239380 0,3
%A A239380 _Chad Brewbaker_, Mar 17 2014