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Number of tilings of a 6 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.
2

%I #8 Dec 07 2012 12:52:47

%S 1,1,2,8,21,65,267,804,2530,9407,29876,96530,337607,1100968,3612017,

%T 12284181,40538721,133971666,450045654,1492504271,4949649998,

%U 16537407509,54951656907,182545459254,608458757050,2023395434235,6727009100372,22399013790607

%N Number of tilings of a 6 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

%H Alois P. Heinz, <a href="/A219970/b219970.txt">Table of n, a(n) for n = 0..600</a>

%e a(2) = 2, because there are 2 tilings of a 6 X 2 rectangle using straight (3 X 1) trominoes and 2 X 2 tiles:

%e ._._. .___.

%e | | | | |

%e | | | |___|

%e |_|_| | |

%e | | | |___|

%e | | | | |

%e |_|_| |___|

%Y Column k=6 of A219967.

%K nonn

%O 0,3

%A _Alois P. Heinz_, Dec 02 2012