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A266936
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Number of 3 X n binary arrays with rows lexicographically nondecreasing and columns lexicographically nondecreasing and row sums nondecreasing and column sums nonincreasing.
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1
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4, 7, 9, 12, 14, 19, 21, 26, 30, 35, 39, 46, 50, 57, 63, 70, 76, 85, 91, 100, 108, 117, 125, 136, 144, 155, 165, 176, 186, 199, 209, 222, 234, 247, 259, 274, 286, 301, 315, 330, 344, 361, 375, 392, 408, 425, 441, 460, 476, 495, 513, 532, 550, 571, 589, 610, 630, 651, 671
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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) = a(n-1) + a(n-2) - a(n-4) - a(n-5) + a(n-6).
Empirical g.f.: x*(4 + 3*x - 2*x^2 - 4*x^3 - 3*x^4 + 4*x^5) / ((1 - x)^3*(1 + x)*(1 + x + x^2)). - Colin Barker, Jan 10 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..0..1....0..0..1..1....1..1..1..1....0..0..1..1....0..0..1..1
..1..1..1..0....1..1..0..1....1..1..1..1....1..1..0..0....1..1..0..0
..1..1..1..0....1..1..1..0....1..1..1..1....1..1..0..0....1..1..1..1
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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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