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A251310
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Number of (n+1) X (1+1) 0..1 arrays with no 2 X 2 subblock having the maximum of its diagonal elements greater than the absolute difference of its antidiagonal elements.
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1
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10, 25, 61, 149, 365, 894, 2189, 5360, 13125, 32139, 78698, 192706, 471875, 1155470, 2829374, 6928226, 16964995, 41541811, 101722521, 249085705, 609930700, 1493523921, 3657159252, 8955205609, 21928415465, 53695629760, 131483310316
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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) = 3*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4).
Empirical g.f.: x*(10 - 5*x + 6*x^2 - 4*x^3) / (1 - 3*x + 2*x^2 - 2*x^3 + x^4). - Colin Barker, Nov 28 2018
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EXAMPLE
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Some solutions for n=4:
..1..1....1..1....1..0....0..0....1..0....0..1....0..1....0..1....1..0....0..1
..0..1....0..0....1..0....0..0....1..0....0..1....0..0....0..1....1..0....0..0
..0..1....0..0....1..1....1..1....1..1....0..0....1..1....0..0....1..0....1..1
..1..0....1..0....0..0....0..1....0..1....1..1....0..1....1..0....1..1....0..1
..1..1....1..1....1..0....0..1....0..0....0..0....1..0....1..0....0..0....0..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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