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A253503
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Number of (n+2) X (1+2) 0..1 arrays with every 2 X 2 and 3 X 3 subblock diagonal maximum minus antidiagonal minimum nondecreasing horizontally and vertically.
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1
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132, 260, 428, 636, 884, 1172, 1500, 1868, 2276, 2724, 3212, 3740, 4308, 4916, 5564, 6252, 6980, 7748, 8556, 9404, 10292, 11220, 12188, 13196, 14244, 15332, 16460, 17628, 18836, 20084, 21372, 22700, 24068, 25476, 26924, 28412, 29940, 31508, 33116
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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) = 20*n^2 + 68*n + 44.
G.f.: 4*x*(33 - 34*x + 11*x^2) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.
(End)
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EXAMPLE
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Some solutions for n=4:
..0..1..1....0..1..1....1..1..1....0..0..0....0..0..0....0..1..1....0..1..0
..1..1..0....0..0..1....1..1..0....1..1..1....0..0..0....1..1..1....1..1..0
..1..1..0....0..0..1....1..1..0....0..0..0....0..0..0....1..1..1....1..1..0
..1..1..0....1..0..1....1..1..1....1..1..1....0..0..0....1..1..0....0..0..0
..1..1..0....1..0..1....1..0..1....0..0..0....0..0..0....1..1..1....1..1..1
..0..1..1....0..0..1....0..0..1....0..1..1....0..1..1....0..0..0....0..0..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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