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A219975 Number of tilings of an n X n square using straight (3 X 1) trominoes and 2 X 2 tiles. 2

%I

%S 1,0,1,2,3,28,267,2744,66653,2766100,141365332,13305552648,

%T 2149055591278

%N Number of tilings of an n X n square using straight (3 X 1) trominoes and 2 X 2 tiles.

%e a(4) = 3, because there are 3 tilings of a 4 X 4 square using straight (3 X 1) trominoes and 2 X 2 tiles:

%e ._._____. ._____._. ._._._._.

%e | |_____| |_____| | | . | . |

%e | | . | | | | . | | |___|___|

%e |_|___| | | |___|_| | . | . |

%e |_____|_| |_|_____| |___|___| .

%Y Main diagonal of A219967.

%Y Cf. A233807.

%K nonn,more

%O 0,4

%A _Alois P. Heinz_, Dec 02 2012

%E a(12) from _Alois P. Heinz_, Sep 24 2014

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Last modified August 15 09:19 EDT 2022. Contains 356135 sequences. (Running on oeis4.)