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A250883
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Number of (6+1) X (n+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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155080, 553736, 1350002, 2681528, 4685964, 7500960, 11264166, 16113232, 22185808, 29619544, 38552090, 49121096, 61464212, 75719088, 92023374, 110514720, 131330776, 154609192, 180487618, 209103704, 240595100, 275099456
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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) = (68825/3)*n^3 + 61155*n^2 + (163798/3)*n + 16384.
G.f.: 2*x*(77540 - 33292*x + 32769*x^2 - 8192*x^3) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4.
(End)
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EXAMPLE
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Some solutions for n=1:
..0..0....2..2....2..2....0..0....2..2....2..2....2..2....2..2....1..1....0..0
..2..2....0..0....3..3....0..0....3..3....0..2....1..1....2..2....2..2....2..2
..0..0....0..1....0..0....1..1....2..2....1..3....3..3....1..2....0..0....1..1
..3..3....0..1....2..2....3..3....0..0....0..2....2..2....1..2....0..0....3..3
..3..3....1..2....3..3....3..3....2..3....1..3....2..2....1..2....0..1....3..3
..1..1....0..2....0..0....1..3....0..1....1..3....0..2....0..1....0..1....1..1
..3..3....0..2....1..1....0..2....0..2....0..3....0..2....1..2....1..2....0..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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