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 A219950 #4 Dec 01 2012 19:40:07 %S A219950 1,0,16,0,560,384,46824,253952,5141408,44013568,628801280,6441106368, %T A219950 81395792936,898467518528,10813539098984,123094927843072, %U A219950 1452323503655432,16743873126866752,195934939996794440,2270867565108570304,26483057736012701952 %N A219950 Number of tilings of a 9 X n rectangle using right trominoes and 2 X 2 tiles. %H A219950 Alois P. Heinz, <a href="/A219950/b219950.txt">Table of n, a(n) for n = 0..300</a> %Y A219950 Column k=9 of A219946. %K A219950 nonn %O A219950 0,3 %A A219950 _Alois P. Heinz_, Dec 01 2012