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A197056
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Number of nX3 0..4 arrays with each element equal to the number its horizontal and vertical neighbors equal to 2
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1
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1, 3, 6, 10, 14, 22, 38, 67, 111, 179, 291, 485, 812, 1348, 2220, 3660, 6060, 10053, 16653, 27541, 45541, 75367, 124786, 206574, 341850, 565666, 936146, 1549447, 2564507, 4244263, 7024071, 11624777, 19239384, 31841864, 52698776, 87216664
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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 2's, every 1 is next to 1 2's, every 2 is next to 2 2's, every 3 is next to 3 2's, every 4 is next to 4 2's
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) +2*a(n-4) +a(n-5) +a(n-6)
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EXAMPLE
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Some solutions for n=4
..2..2..2....1..2..2....0..0..0....0..1..1....2..2..1....0..0..0....1..1..1
..2..3..2....1..2..2....1..1..0....1..2..2....2..2..1....0..1..1....2..2..2
..2..3..2....0..1..1....2..2..1....1..2..2....1..1..0....1..2..2....2..4..2
..2..2..2....0..0..0....2..2..1....0..1..1....0..0..0....1..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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STATUS
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approved
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