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A205830
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Number of (n+1) X 3 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to two.
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1
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111, 630, 3642, 21126, 122526, 710526, 4120230, 23892558, 138549222, 803425470, 4658939862, 27016470606, 156664328166, 908472171486, 5268089398710, 30548834388078, 177147958555782, 1027253571178110, 5956884336128982
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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) = 7*a(n-1) -8*a(n-2) +6*a(n-3) for n>4.
Empirical g.f.: 3*x*(37 - 49*x + 40*x^2 + 2*x^3) / (1 - 7*x + 8*x^2 - 6*x^3). - Colin Barker, Jun 13 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..1....1..2..0....2..1..1....0..0..1....2..1..0....2..1..1....0..2..1
..2..0..2....1..0..1....1..0..2....2..1..2....0..2..1....1..0..2....2..1..2
..2..1..0....2..1..0....2..1..0....0..2..0....1..0..2....2..1..0....0..2..0
..1..0..1....0..2..1....0..2..1....2..1..2....2..1..0....0..2..1....2..0..2
..0..1..2....2..1..2....1..0..2....1..2..1....0..2..1....2..0..2....0..1..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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