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A229421
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Number of n X n 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, rows lexicographically nondecreasing, and columns lexicographically nonincreasing.
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2
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3, 12, 83, 754, 7816, 87648, 1037193, 12768612, 162034856, 2106287556, 27919532994, 376116911288, 5136301331502, 70961712401226, 990271481453131, 13940677426765198, 197768065242681646, 2824828320413979786, 40595088421065998006, 586585037559246948950
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Some solutions for n=4
..1..1..0..0....1..1..1..1....0..0..0..0....2..2..1..1....2..1..1..0
..1..1..0..0....2..1..1..1....1..1..0..0....2..2..2..1....2..1..1..0
..2..1..1..0....2..2..1..1....2..1..1..1....2..2..2..1....2..1..1..1
..2..1..1..0....2..2..2..1....2..2..2..1....2..2..2..2....2..2..2..2
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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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STATUS
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approved
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