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A253152
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Number of (n+1) X (1+1) 0..1 arrays with every 2 X 2 subblock diagonal minus antidiagonal sum nondecreasing horizontally and vertically.
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2
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16, 39, 69, 109, 181, 325, 613, 1189, 2341, 4645, 9253, 18469, 36901, 73765, 147493, 294949, 589861, 1179685, 2359333, 4718629, 9437221, 18874405, 37748773, 75497509, 150994981, 301989925, 603979813, 1207959589, 2415919141, 4831838245
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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) = 3*a(n-1) -2*a(n-2) for n>5.
Empirical: a(n) = 9*2^(n-1) + 37 for n>3.
Empirical g.f.: x*(16 - 9*x - 16*x^2 - 20*x^3 - 8*x^4) / ((1 - x)*(1 - 2*x)). - Colin Barker, Mar 20 2018
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EXAMPLE
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Some solutions for n=6:
..0..1....0..1....0..0....0..0....0..1....0..1....1..1....0..0....0..1....0..0
..1..1....0..0....1..1....0..0....1..1....1..1....1..1....0..0....0..0....1..1
..1..1....1..1....1..1....0..0....0..0....1..1....1..1....0..0....1..1....0..0
..0..0....0..0....1..1....0..0....1..1....1..1....1..1....1..1....0..0....0..0
..0..0....1..1....0..0....1..1....1..1....0..0....1..1....0..0....1..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....1..1....1..1
..0..0....1..1....0..1....1..1....0..0....1..1....0..1....1..1....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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