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A250834
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Number of (n+1) X (1+1) 0..2 arrays with no 2 X 2 subblock having a diagonal absolute difference less than its antidiagonal absolute difference.
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1
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55, 333, 2011, 12145, 73351, 443013, 2675635, 16159849, 97599535, 589465245, 3560152987, 21502012897, 129864239095, 784332177525, 4737077497219, 28610203505305, 172795092564223, 1043618721857421, 6303072734583595
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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) = 8*a(n-1) - 13*a(n-2) + 8*a(n-3) - 6*a(n-4).
Empirical g.f.: x*(55 - 107*x + 62*x^2 - 54*x^3) / (1 - 8*x + 13*x^2 - 8*x^3 + 6*x^4). - Colin Barker, Nov 21 2018
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EXAMPLE
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Some solutions for n=4:
..1..1....1..0....1..1....1..0....0..0....2..1....1..1....2..1....1..0....0..0
..2..0....0..1....2..2....0..1....1..1....0..0....2..0....1..0....0..0....1..2
..1..0....2..2....0..0....0..2....2..0....0..2....1..0....0..1....2..2....1..2
..0..2....2..1....1..1....1..1....0..2....2..0....0..0....0..2....2..1....2..0
..1..2....2..1....2..2....0..0....2..0....0..2....1..1....1..2....1..2....1..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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