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A200045 Number T(n,m) of ways of 4-coloring an n X m grid so that there is no rectangle with all 4 corners the same color. 3
4, 16, 252, 64, 3912, 228984, 256, 59928, 12870096, 2545607472, 1024, 906912, 696448224, 465659203104, 272454472598400, 4096, 13571712, 36376835616, 79102304162784, 140221913588582784 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..20.

J. D. Davies, Number of unique rectangle-free 4-colourings for an nxm grid

EXAMPLE

Triangle starts:

4;

16, 252;

64, 3912, 228984;

256, 59928, 12870096, 2545607472;

1024, 906912, 696448224, 465659203104, 272454472598400;

...

CROSSREFS

Cf. A252778, A252780, A252839.

Sequence in context: A271267 A232840 A113905 * A099202 A139288 A152921

Adjacent sequences:  A200042 A200043 A200044 * A200046 A200047 A200048

KEYWORD

nonn,tabl,more

AUTHOR

Jason Davies, Nov 14 2011

EXTENSIONS

T(6,5) from Jason Davies, Nov 08 2012

STATUS

approved

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Last modified January 23 21:40 EST 2017. Contains 281216 sequences.