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A183691
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Number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock nonsingular.
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1
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314, 4594, 66658, 969978, 14100346, 205047906, 2981428242, 43352455562, 630370287594, 9166011482354, 133279732667138, 1937974996756378, 28179423476635226, 409747282346950786, 5957993760514619122
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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) = 8*a(n-1) + 91*a(n-2) + 74*a(n-3) - 208*a(n-4).
Empirical g.f.: 2*x*(157 + 1041*x + 666*x^2 - 2288*x^3) / (1 - 8*x - 91*x^2 - 74*x^3 + 208*x^4). - Colin Barker, Apr 04 2018
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EXAMPLE
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Some solutions for 5 X 3:
..0..2..0....0..2..0....0..1..2....0..2..0....0..1..0....0..1..1....0..1..0
..1..2..1....2..2..2....2..1..0....2..2..1....2..1..1....1..1..0....1..0..2
..2..0..1....1..0..1....2..0..2....2..0..1....1..2..0....2..1..2....2..2..2
..2..1..2....0..2..1....2..1..2....1..2..0....2..1..2....0..1..1....0..1..0
..1..0..2....1..2..2....2..0..1....1..1..1....1..0..1....1..2..0....2..0..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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