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 A239371 #12 Oct 02 2014 07:51:55
%S A239371 1,1,4,27,252,2935,40351,633864,11139840,215800335,4557031407,
%T A239371 103989209082,2546369980589,66521801043100,1845008781481516,
%U A239371 54102505102771686,1671315770146956704,54219694639758864087,1842085959295755494339,65380444351870047159358
%N A239371 Words of length n over the alphabet {0,...,n-1} that avoid the pattern 1123.
%H A239371 Hiroaki Yamanouchi, <a href="/A239371/b239371.txt">Table of n, a(n) for n = 0..24</a>
%Y A239371 Cf. A239295.
%K A239371 nonn
%O A239371 0,3
%A A239371 _Chad Brewbaker_, Mar 17 2014
%E A239371 a(8)-a(15) from _Alois P. Heinz_, Mar 17 2014
%E A239371 a(16)-a(19) from _Hiroaki Yamanouchi_, Oct 02 2014