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A183485
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Number of n X 2 0..3 arrays with every element equal to either the sum mod 4 of its vertical neighbors or the sum mod 4 of its horizontal neighbors.
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1
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4, 28, 88, 400, 1936, 8368, 38272, 176320, 800512, 3661312, 16761088, 76588288, 350288896, 1602288640, 7327467520, 33513336832, 153280811008, 701043896320, 3206335627264, 14664712241152, 67071268225024, 306761100427264
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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) = 4*a(n-1) + 24*a(n-3) - 48*a(n-4) - 144*a(n-6).
Empirical g.f.: 4*x*(1 + 3*x - 6*x^2 - 12*x^3 - 36*x^4 - 36*x^5) / ((1 - 12*x^3)*(1 - 4*x - 12*x^3)). - Colin Barker, Mar 29 2018
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EXAMPLE
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Some solutions for 3 X 2.
..3..3....1..0....0..2....0..0....3..2....3..3....0..0....3..3....0..0....1..1
..2..2....1..0....0..2....3..2....3..2....0..0....3..0....1..1....3..3....0..0
..2..2....0..0....0..0....3..2....0..0....3..3....3..0....2..2....3..3....3..3
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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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