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A250633
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Number of (1+1) X (n+1) 0..2 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.
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1
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36, 154, 585, 2183, 7924, 28456, 101308, 358990, 1268051, 4470464, 15740673, 55379788, 194741827, 684584785, 2406055663, 8455258981, 29710611016, 104393359779, 366791460582, 1288712370834, 4527794056964, 15907920902171
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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) - 2*a(n-2) - 14*a(n-3) + 7*a(n-4) + 10*a(n-5) - 5*a(n-6) - 2*a(n-7) + a(n-8).
Empirical g.f.: x*(36 - 26*x - 113*x^2 + 70*x^3 + 83*x^4 - 46*x^5 - 17*x^6 + 9*x^7) / ((1 - 2*x - x^2 + x^3)*(1 - 3*x - 3*x^2 + 4*x^3 + x^4 - x^5)). - Colin Barker, Nov 15 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..0..1..1....0..0..0..0..0....0..0..0..1..2....0..0..0..0..0
..0..1..2..2..2....0..0..1..1..0....2..2..1..1..2....0..1..1..2..0
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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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