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A206791
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Number of n X 2 0..3 arrays avoiding the pattern z z+1 z in any row, column, diagonal or antidiagonal.
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4
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16, 256, 3721, 53824, 779689, 11296321, 163660849, 2371105636, 34352398336, 497694975625, 7210567562500, 104466163115161, 1513497951497401, 21927445030264225, 317683182247352464, 4602570164626581904
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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) = 15*a(n-1) -11*a(n-2) +51*a(n-3) +13*a(n-4) -3*a(n-5) -a(n-6).
Empirical g.f.: x*(16 + 16*x + 57*x^2 + 9*x^3 - 4*x^4 - x^5) / ((1 - x + 4*x^2 - x^3)*(1 - 14*x - 7*x^2 - x^3)). - Colin Barker, Feb 20 2018
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EXAMPLE
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Some solutions for n=4:
..0..2....3..3....0..2....1..3....1..3....2..3....3..1....3..1....2..0....1..1
..1..1....0..1....2..1....0..0....2..1....3..0....1..2....1..1....1..0....1..3
..3..1....0..0....1..0....1..3....2..1....1..2....0..2....3..3....2..0....3..3
..0..0....3..2....1..1....2..2....0..3....3..2....0..0....3..1....2..2....2..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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