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 A219951 #4 Dec 01 2012 19:39:32 %S A219951 1,0,25,32,1426,8120,212926,2175992,45081311,628801280,11112714624, %T A219951 173179768136,2908344290540,46894928400912,774211745673930, %U A219951 12617601589397384,207178457948099771,3387766419366893632,55527737283695335309,908939402189646871904 %N A219951 Number of tilings of a 10 X n rectangle using right trominoes and 2 X 2 tiles. %H A219951 Alois P. Heinz, <a href="/A219951/b219951.txt">Table of n, a(n) for n = 0..250</a> %Y A219951 Column k=10 of A219946. %K A219951 nonn %O A219951 0,3 %A A219951 _Alois P. Heinz_, Dec 01 2012