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A201621
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Number of nX4 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor
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1
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10, 211, 3699, 91223, 2111763, 45733593, 891142897, 15644678596, 249289360661, 3639136663173, 49094967861596, 616937242119695, 7271050760251026, 80851029109219123, 852557302953238048, 8562810135696296292
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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Some solutions for n=4
..1..1..3..3....0..2..2..2....0..0..2..2....0..0..3..3....0..2..2..2
..1..2..2..2....0..2..3..3....0..2..2..2....2..2..2..2....0..2..3..3
..2..2..0..0....1..0..0..3....0..2..2..3....2..3..1..1....3..2..0..0
..2..2..0..0....1..1..1..3....0..3..3..3....2..3..3..3....3..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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STATUS
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approved
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