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A250609
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Number of (n+1) X (6+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction.
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1
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502, 1172, 2236, 3890, 6526, 10928, 18664, 32870, 59818, 112052, 214660, 417818, 821878, 1627544, 3236224, 6450734, 12876706, 25725404, 51419356, 102803618, 205568302, 411093632, 822140056, 1644228470, 3288400666, 6576740228
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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) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4).
Empirical: a(n) = 196*2^(n-1) + 99*n^2 + 177*n + 30.
Empirical g.f.: 2*x*(251 - 669*x + 447*x^2 - 128*x^3) / ((1 - x)^3*(1 - 2*x)). - Colin Barker, Nov 15 2018
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EXAMPLE
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Some solutions for n=6:
..1..0..1..1..0..1..0....1..1..1..1..1..0..0....0..0..0..0..0..0..0
..1..0..1..1..0..1..1....0..0..0..0..1..0..0....1..1..1..1..1..1..1
..0..0..1..1..0..1..1....0..0..0..0..1..0..0....0..0..0..0..0..0..0
..0..0..1..1..0..1..1....0..0..0..0..1..0..0....1..1..1..1..1..1..1
..0..0..1..1..0..1..1....0..0..0..0..1..0..1....1..1..1..1..1..1..1
..0..0..1..1..0..1..1....0..0..0..0..1..0..1....0..0..0..0..0..0..0
..0..0..1..1..0..1..1....0..0..0..0..1..0..1....0..0..0..1..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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