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A250943
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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 absolute value of x(i,j)-x(i-1,j) in the j direction.
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1
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37, 155, 599, 2247, 8189, 29281, 103093, 358683, 1235935, 4225319, 14350733, 48472137, 162955925, 545627419, 1820560999, 6056081319, 20091759229, 66499907441, 219643052501, 724114352379, 2383286792687, 7832488669255
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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) = 6*a(n-1) - 6*a(n-2) - 15*a(n-3) + 14*a(n-4) + 12*a(n-5).
Empirical g.f.: x*(37 - 67*x - 109*x^2 + 138*x^3 + 108*x^4) / ((1 - 3*x)*(1 - x - x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 23 2018
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EXAMPLE
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Some solutions for n=4:
0 1 1 2 0 0 1 0 0 0 0 1 0 2 0 1 0 0 0 2
0 1 1 2 0 0 1 1 1 1 1 0 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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