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A166197
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Number of nXnXn triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= 2
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2
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1, 3, 1, 2, 6, 12, 26, 90, 200, 665, 3980, 10515, 52518, 433447, 1973317, 14252749, 166762668, 1065468116, 11148385916, 193707228525, 1758897674635, 26740845738267, 672553810724428, 9032785397690122, 199494539604910376
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OFFSET
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0,2
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LINKS
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EXAMPLE
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All solutions for n=4
.....0........1........1........0........2........0...
....0.0......0.0......0.0......0.0......0.0......0.0..
...0.2.0....0.0.0....0.1.0....0.0.0....0.0.0....0.1.0.
..0.0.0.0..1.0.0.1..1.0.0.1..0.0.0.0..2.0.0.2..0.0.0.0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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