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A200045 Number of ways of 4-coloring an n x m grid so that there is no rectangle with all 4 corners the same color. 0

%I

%S 4,16,252,64,3912,228984,256,59928,12870096,2545607472,1024,906912,

%T 696448224,465659203104,272454472598400,4096,13571712,36376835616,

%U 79102304162784,140221913588582784

%N Number of ways of 4-coloring an n x m grid so that there is no rectangle with all 4 corners the same color.

%C The rectangles have sides parallel to the x- and y-axes.

%H J. D. Davies <a href="http://www.jasondavies.com/17x17/">Number of unique rectangle-free 4-colourings for an nxm grid</a>

%K nonn,tabl

%O 1,1

%A _Jason Davies_, Nov 14 2011

%E a(20) from _Jason Davies_, Nov 08 2012

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Last modified April 24 12:03 EDT 2014. Contains 240983 sequences.