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A233094
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Number of n X 4 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, diagonally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order.
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1
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14, 386, 11486, 342626, 10221326, 304926626, 9096692126, 271376130626, 8095800458126, 241517133090626, 7205034990428126, 214943464047390626, 6412278746469578126, 191293645073850390626, 5706747958483163828126
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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) = 31*a(n-1) - 35*a(n-2) + 5*a(n-3).
G.f.: 2*x*(7 - 24*x + 5*x^2) / ((1 - x)*(1 - 30*x + 5*x^2)).
a(n) = (110 + (15-2*sqrt(55))^n*(55+sqrt(55)) - (-55+sqrt(55))*(15+2*sqrt(55))^n) / 110.
(End)
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EXAMPLE
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Some solutions for n=3:
..0..0..1..0....0..1..0..2....0..1..1..3....0..1..3..3....0..1..1..1
..2..0..0..1....3..1..0..0....3..1..3..1....3..1..1..3....1..0..0..1
..1..0..0..0....0..2..0..1....0..2..0..1....3..1..1..0....1..1..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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