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A208410
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Number of 3 X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
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1
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5, 187, 10682, 658450, 40883360, 2540446156, 157873031498, 9810914663050, 609693293454056, 37889020302613060, 2354590230800815490, 146324584692741696562, 9093252748398554214416, 565094688091663621180732
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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) = 62*a(n-1) + 39*a(n-2) - 1790*a(n-3) - 4703*a(n-4) - 1254*a(n-5) + 3249*a(n-6) + 918*a(n-7) - 648*a(n-8) for n>10.
Empirical g.f.: x*(1 + x)*(2 - 23*x - 3*x^2 + 22*x^3 + 8*x^4) / ((1 - 3*x - 2*x^2)*(1 - 15*x - 12*x^2)). - Colin Barker, Jul 02 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..0..0....0..0..1..0....0..1..1..1....0..1..1..1....0..0..0..0
..0..1..1..2....0..0..0..0....0..2..3..0....0..0..0..1....0..1..0..0
..0..1..0..0....1..1..1..0....1..1..1..1....0..1..0..0....1..2..3..2
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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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