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A231338
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Number of (n+1) X (2+1) 0..3 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with values 0..3 introduced in row major order.
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1
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4, 9, 22, 59, 159, 439, 1236, 3527, 10184, 29679, 87109, 257077, 761860, 2264909, 6749138, 20146867, 60218835, 180167387, 539423380, 1615890811, 4842424660, 14515699655, 43521570985, 130508409225, 391401045892, 1173929246129
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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) = 5*a(n-1) - 6*a(n-2) + 2*a(n-3) - 8*a(n-4) + 6*a(n-5) - a(n-6) + 3*a(n-7).
Empirical g.f.: x*(4 - 11*x + x^2 - 5*x^3 + 10*x^4 + 2*x^5 + 3*x^6) / ((1 - x)*(1 - 3*x)*(1 + x + x^2)*(1 - 2*x - x^3)). - Colin Barker, Sep 28 2018
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EXAMPLE
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Some solutions for n=6:
..0..0..1....0..0..1....0..1..1....0..0..1....0..0..0....0..0..0....0..0..0
..0..0..1....0..0..1....0..1..1....0..0..1....1..1..1....1..1..0....1..1..1
..1..1..1....1..1..1....0..1..1....1..1..1....1..1..1....1..1..0....1..1..1
..1..2..2....1..1..1....0..1..1....1..0..0....2..2..2....0..0..0....1..1..1
..1..2..2....1..1..1....0..0..0....1..0..0....2..2..2....0..0..0....0..0..0
..1..1..2....1..1..1....1..1..0....1..2..2....2..2..2....2..2..2....0..0..0
..1..1..2....0..0..0....1..1..0....1..2..2....3..3..3....2..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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