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A186471
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Number of (n+1)X9 0..2 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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4553, 5790, 13985, 31866, 52755, 109950, 170811, 399018, 570183, 1266414, 1812423, 3993474, 6107001, 13004678, 20863681, 42650908, 70588930, 140178754, 237788174, 462275652, 798678366, 1528016844, 2676404634, 5059638908, 8953777234
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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)+a(n-2)-4*a(n-3)+4*a(n-4)-2*a(n-5) for n>17
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EXAMPLE
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Some solutions for 3X9
..1..0..1..0..0..0..0..1..2....0..0..0..2..0..0..0..0..0
..0..1..0..1..0..0..0..0..1....1..0..0..0..2..0..0..0..0
..0..0..1..0..1..0..0..0..0....0..1..0..0..0..2..0..0..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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