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A208303
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Number of 3 X n nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or antidiagonal neighbor (colorings ignoring permutations of colors).
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2
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1, 5, 52, 2906, 373780, 87852626, 33093356640, 18383354934430, 14216420560211868, 14670987603972303070, 19558496205580909812744, 32828323774419481541135978, 67939294184199439807451132308, 170381709310740181061939305134514, 510275358861788633812686061715278224
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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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Some solutions for n=4:
..0..1..2..0....0..1..0..1....0..1..0..2....0..1..0..1....0..1..2..0
..2..1..2..0....0..1..0..1....3..1..0..2....0..1..0..1....3..0..1..0
..0..3..1..0....0..1..2..1....0..1..0..1....2..1..2..0....1..0..3..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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EXTENSIONS
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a(0)=1 prepended and terms a(10) and beyond from Andrew Howroyd, May 18 2020
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STATUS
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approved
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