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A250874
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Number of (n+1) X (5+1) 0..3 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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2306, 11644, 55386, 250964, 1097986, 4685964, 19649066, 81358084, 333810066, 1360557884, 5518553146, 22303914804, 89906240546, 361699655404, 1453028599626, 5830816129124, 23379393301426, 93686006746524
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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) = 10*a(n-1) - 35*a(n-2) + 50*a(n-3) - 24*a(n-4); a(n) = (4112*4^n - 3915*3^n + 1080*2^n + 55)/3.
Empirical g.f.: 2*x*(1153 - 5708*x + 9828*x^2 - 5328*x^3) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)). - Colin Barker, Nov 22 2018
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EXAMPLE
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Some solutions for n=3:
..2..2..2..2..2..2....2..2..2..2..2..2....3..3..3..3..3..3....2..2..2..2..2..1
..1..1..1..1..1..1....0..0..0..2..2..2....1..2..3..3..3..3....1..1..1..1..1..2
..0..0..0..0..0..0....1..1..1..3..3..3....1..2..3..3..3..3....0..0..0..0..0..1
..0..0..1..1..1..2....0..0..0..2..3..3....0..2..3..3..3..3....0..0..0..0..2..3
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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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