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A237227
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Number of (n+1) X (1+1) 0..2 arrays with the maximum plus the minimum of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one.
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1
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81, 268, 928, 2784, 9628, 28912, 100008, 300256, 1038560, 3118208, 10785696, 32383104, 112011072, 336303872, 1163253760, 3492571136, 12080581376, 36270926848, 125458829824, 376679553024, 1302910621696, 3911879237632
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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) = 8*a(n-2) + 24*a(n-4) + 8*a(n-6) for n>7.
Empirical g.f.: x*(81 + 268*x + 280*x^2 + 640*x^3 + 260*x^4 + 208*x^5 + 64*x^6) / ((1 + 2*x^2)*(1 - 10*x^2 - 4*x^4)). - Colin Barker, Oct 21 2018
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EXAMPLE
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Some solutions for n=5:
..2..1....1..2....0..2....1..0....0..2....2..1....2..0....1..0....2..1....2..1
..0..0....0..0....1..0....2..1....0..0....2..2....0..1....1..0....1..0....0..0
..1..0....1..0....0..1....1..1....1..0....0..1....0..0....2..1....1..1....1..0
..2..2....2..2....2..2....1..1....1..2....0..1....2..2....1..2....1..1....2..2
..1..1....1..2....1..1....2..2....1..1....1..2....1..2....0..1....0..0....1..2
..0..2....1..0....1..1....0..0....0..2....2..1....2..0....0..1....0..2....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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