

A356523


a(n) is the number of tilings of the Aztec diamond of order n using dominoes and horizontal straight tetrominoes.


1



1, 2, 11, 209, 12748, 2432209, 1473519065, 2827837404882, 17158790773744279, 329479797284568074621, 20021122370390985464701796, 3849702362426399132776261664897, 2342395734889640880082957470488832361
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OFFSET

0,2


COMMENTS

It appears that a(n) is even when n is congruent to 1 (mod 3) and is odd otherwise.


LINKS



EXAMPLE

For n=2 there are 8 ways to tile using just dominoes, and 3 ways to tile using one or more horizontal straight tetrominoes (in the second row, third row, or both), for a total of 11 tilings.


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



