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 A239376 #10 Mar 19 2014 13:01:55
%S A239376 1,1,4,27,252,2935,40330,632352,11070192,213109881,4460816992,
%T A239376 100651469996,2431215093846,62514061904580,1703115911340272,
%U A239376 48965931282533948,1480607510447121328,46944740372499336665
%N A239376 Words of length n over the alphabet {0,...,n-1} that avoid the pattern 1223.
%Y A239376 Cf. A239295.
%K A239376 nonn,more
%O A239376 0,3
%A A239376 _Chad Brewbaker_, Mar 17 2014
%E A239376 a(8)-a(17) from _Alois P. Heinz_, Mar 19 2014