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A251003
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Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having its maximum diagonal element less than the absolute difference of its antidiagonal elements.
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1
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69, 530, 4083, 31456, 242326, 1866789, 14381065, 110786519, 853459216, 6574740657, 50649420520, 390184789500, 3005842285913, 23155920197037, 178384821680265, 1374212051826542, 10586431881352371, 81554036605596548
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 9*a(n-1) - 12*a(n-2) + 17*a(n-3) - 12*a(n-4) + 4*a(n-5).
Empirical g.f.: x*(69 - 91*x + 141*x^2 - 104*x^3 + 36*x^4) / (1 - 9*x + 12*x^2 - 17*x^3 + 12*x^4 - 4*x^5). - Colin Barker, Nov 24 2018
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EXAMPLE
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Some solutions for n=4:
..0..0....1..2....0..0....1..0....0..0....1..1....0..2....2..1....2..0....1..0
..1..2....2..2....0..2....0..0....0..1....2..2....2..0....0..2....0..2....0..1
..2..0....2..2....2..1....2..2....1..2....2..1....1..0....2..0....2..1....1..0
..2..1....2..0....2..1....1..2....2..2....2..1....1..1....2..0....1..2....1..1
..2..2....0..0....2..0....0..2....1..2....0..1....0..0....2..2....1..2....2..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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