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A203958
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Number of (n+1) X 2 0..2 arrays with column and row pair sums b(i,j)=a(i,j)+a(i,j-1) and c(i,j)=a(i,j)+a(i-1,j) such that rows of b(i,j) and columns of c(i,j) are lexicographically nondecreasing.
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1
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32, 121, 447, 1579, 5352, 17559, 56219, 176797, 548760, 1687165, 5151519, 15651063, 47379056, 143054539, 431129547, 1297582777, 3901661040, 11723857281, 35211417503, 105718138339, 317330575512, 952360824991, 2857854226587
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 10*a(n-1) -40*a(n-2) +82*a(n-3) -91*a(n-4) +52*a(n-5) -12*a(n-6).
Empirical g.f.: x*(32 - 199*x + 517*x^2 - 675*x^3 + 432*x^4 - 108*x^5) / ((1 - x)^3*(1 - 2*x)^2*(1 - 3*x)). - Colin Barker, Jun 06 2018
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EXAMPLE
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Some solutions for n=4:
..1..2....2..0....0..0....1..1....0..2....0..2....1..2....2..1....2..1....2..2
..1..2....0..2....2..2....1..1....0..2....1..1....1..2....1..2....1..2....2..2
..1..2....2..0....2..2....0..2....2..0....1..1....2..1....2..2....2..1....2..2
..1..2....0..2....2..2....2..1....0..2....0..2....1..2....2..2....1..2....2..2
..1..2....1..1....2..2....2..1....1..2....1..2....2..1....2..2....2..1....2..2
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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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