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A199143
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Number of nX2 0..3 arrays with values 0..3 introduced in row major order and each element equal to one or two horizontal and vertical neighbors
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1
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1, 3, 13, 65, 393, 2539, 16866, 113432, 766473, 5188597, 35148945, 238173743, 1614066774, 10938730576, 74134306725, 502428413393, 3405102418833, 23077383280435, 156402287318610, 1059984943413152, 7183834447992225
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 7*a(n-1) +2*a(n-2) -16*a(n-3) -49*a(n-4) -35*a(n-5) +56*a(n-6) +54*a(n-7) +45*a(n-8) -27*a(n-9) for n>11
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EXAMPLE
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Some solutions for n=4
..0..0....0..0....0..0....0..0....0..1....0..1....0..0....0..1....0..1....0..0
..0..1....0..0....1..2....1..0....0..1....0..1....1..0....0..1....0..1....0..1
..1..1....1..1....1..2....1..0....1..1....0..1....1..0....1..2....0..0....0..1
..0..0....0..0....1..1....1..1....2..2....1..1....1..0....1..2....1..1....0..1
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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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