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A253345
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Number of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock diagonal maximum minus antidiagonal maximum nondecreasing horizontally, vertically and ne-to-sw antidiagonally.
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1
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125, 724, 4800, 30920, 199512, 1285960, 8289288, 53433608, 344449224, 2220470152, 14314275912, 92277661448, 594874191816, 3834903188104, 24722024949576, 159372675116552, 1027409972582088, 6623289504223624, 42697625485315656
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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) - 8*a(n-2) - 72*a(n-3) + 96*a(n-4) + 128*a(n-5) - 128*a(n-6) - 64*a(n-7) for n>8.
Empirical g.f.: x*(125 - 401*x - 716*x^2 + 2512*x^3 - 240*x^4 - 2192*x^5 + 512*x^6 + 512*x^7) / ((1 - 2*x)*(1 - 2*x - 4*x^2)*(1 - 5*x - 12*x^2 + 16*x^3 + 8*x^4)). - Colin Barker, Dec 11 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..1..1....1..0..0..0....1..1..1..1....0..0..0..1....0..0..1..1
..0..1..1..1....1..1..1..1....0..0..0..0....1..1..1..1....0..0..1..0
..0..1..0..0....1..0..0..1....0..0..0..0....0..1..1..1....0..0..1..1
..0..1..0..0....1..1..1..1....1..1..1..1....1..1..1..1....1..1..1..0
..1..1..1..1....0..0..1..1....0..0..1..0....1..1..1..0....0..1..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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