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A239179
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Number of (1+1) X (n+1) 0..2 arrays with no element greater than all horizontal neighbors or equal to all vertical neighbors.
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1
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6, 26, 98, 378, 1512, 6018, 23890, 94846, 376670, 1495888, 5940530, 23591238, 93686602, 372052590, 1477512180, 5867563418, 23301534646, 92536114306, 367483625614, 1459367686212, 5795507324598, 23015382256774, 91399732715398
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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) = 4*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - 4*a(n-5) + a(n-6).
Empirical g.f.: 2*x*(3 + x - 3*x^3 + x^4) / (1 - 4*x + x^2 - 3*x^3 - 3*x^4 + 4*x^5 - x^6). - Colin Barker, Oct 25 2018
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EXAMPLE
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Some solutions for n=5:
..1..1..0..1..1..1....1..1..1..0..1..1....1..1..1..1..1..0....0..0..1..2..2..1
..0..0..2..2..2..2....2..2..2..2..2..2....0..0..0..2..2..1....1..2..2..0..0..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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