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A186476
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Number of (n+1)X4 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors
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1
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1098, 701, 4686, 4810, 20224, 21760, 82632, 101108, 344804, 465884, 1445243, 2112183, 6085048, 9483898, 25738600, 42272077, 109291705, 187344208, 465619270, 826593388, 1989294067, 3634249423, 8519209648, 15933856258, 36556619512
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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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FORMULA
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Empirical: a(n)=2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-4)-3*a(n-5) for n>14
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EXAMPLE
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Some solutions for 3X4
..2..0..1..0....2..2..2..0....0..0..1..1....0..3..0..2....0..1..0..3
..0..2..0..1....0..0..0..2....0..0..0..1....2..0..3..0....0..0..1..0
..2..0..2..2....0..0..0..2....1..0..0..0....0..2..0..3....0..0..0..1
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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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