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A197210
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Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,3,2,1,0 for x=0,1,2,3,4.
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0
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OFFSET
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1,2
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COMMENTS
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Every 0 is next to 0 4's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 1's, every 4 is next to 4 0's.
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LINKS
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EXAMPLE
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Some solutions for n=4
..1..3..1..0....1..3..1..0....1..3..1..1....0..0..0..0....2..2..0..0
..1..1..0..0....0..1..1..0....0..1..1..3....0..1..2..2....2..2..0..0
..3..1..1..0....0..1..3..1....0..0..0..1....1..3..2..2....0..1..0..0
..1..1..3..1....0..0..0..0....0..0..0..0....0..1..0..0....1..3..1..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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