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A250765
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Number of (n+1) X (4+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.
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1
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68, 114, 196, 350, 648, 1234, 2396, 4710, 9328, 18554, 36996, 73870, 147608, 295074, 589996, 1179830, 2359488, 4718794, 9437396, 18874590, 37748968, 75497714, 150995196, 301990150, 603980048, 1207959834, 2415919396, 4831838510
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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) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3); a(n) = 36*2^(n-1) + 10*n + 22.
Empirical g.f.: 2*x*(34 - 79*x + 40*x^2) / ((1 - x)^2*(1 - 2*x)). - Colin Barker, Nov 18 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..0..0..0....1..1..1..1..0....1..1..1..1..1....1..0..1..0..0
..1..1..0..0..0....1..1..1..1..0....0..0..0..0..0....1..0..1..0..0
..1..1..1..1..1....1..1..1..1..0....0..0..0..0..0....1..0..1..0..0
..1..1..1..1..1....1..1..1..1..0....0..0..0..0..0....1..0..1..0..1
..1..1..1..1..1....1..1..1..1..0....1..1..1..1..1....1..0..1..0..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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