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A206341
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Number of (n+1)X7 0..3 arrays with every 2X2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor
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1
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880, 1589, 2030, 4711, 6090, 14181, 18258, 42351, 54654, 126861, 163842, 380391, 491406, 1141143, 1474206, 3423417, 4422606, 10270239, 13267806, 30810705, 39803406, 92432103, 119410206, 277296297, 358230606, 831888879, 1074691806
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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) = a(n-1) +3*a(n-2) -3*a(n-3) for n>15
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EXAMPLE
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Some solutions for n=4
..0..1..0..1..0..2..0....1..0..1..0..1..0..1....3..3..0..2..0..2..0
..3..0..1..0..1..0..2....0..1..0..1..0..1..0....2..0..3..0..2..0..2
..0..3..0..1..0..1..0....1..0..1..0..1..0..1....0..2..0..3..0..2..0
..1..0..3..0..1..0..1....0..1..0..1..0..1..0....1..0..2..0..3..0..2
..0..1..0..3..0..1..1....1..0..1..0..1..0..1....0..1..0..2..0..3..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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