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A183425
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Half the number of n X 2 0..2 arrays with no element equal its row sum plus its column sum mod 3.
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1
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3, 9, 32, 129, 513, 2048, 8193, 32769, 131072, 524289, 2097153, 8388608, 33554433, 134217729, 536870912, 2147483649, 8589934593, 34359738368, 137438953473, 549755813889, 2199023255552, 8796093022209, 35184372088833, 140737488355328
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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) + a(n-3) - 4*a(n-4).
Empirical g.f.: x*(3 - 3*x - 4*x^2 - 2*x^3) / ((1 - x)*(1 - 4*x)*(1 + x + x^2)). - Colin Barker, Mar 29 2018
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EXAMPLE
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Some solutions for 4 X 2:
..1..2....2..2....0..1....2..1....0..2....1..1....0..0....2..1....1..1....0..2
..0..2....2..2....0..1....1..2....0..0....1..2....0..1....0..1....1..2....1..0
..1..2....2..2....0..1....1..2....1..2....0..2....0..0....2..2....2..2....0..0
..1..1....2..2....0..1....2..1....1..0....1..2....1..0....2..1....2..1....1..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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