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A207306
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Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 1 0 vertically.
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2
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6, 36, 98, 271, 665, 1675, 4344, 11081, 28136, 71908, 183709, 468421, 1195165, 3050758, 7784759, 19863812, 50690966, 129357269, 330093729, 842344955, 2149538940, 5485269169, 13997500468, 35719380356, 91150094557, 232600215969
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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) = a(n-1) + a(n-2) + 6*a(n-3) + 4*a(n-4) + a(n-5) - 2*a(n-6) - 2*a(n-7) for n>9.
Empirical g.f.: x*(6 + 30*x + 56*x^2 + 101*x^3 + 56*x^4 + x^5 - 38*x^6 - 26*x^7 - 2*x^8) / (1 - x - x^2 - 6*x^3 - 4*x^4 - x^5 + 2*x^6 + 2*x^7). - Colin Barker, Mar 05 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..1..0....0..0..1..1....1..1..1..1....0..1..0..0....1..1..1..1
..0..0..1..0....0..1..0..0....1..1..1..1....0..0..1..0....1..1..0..0
..0..0..1..0....0..1..0..0....1..1..1..1....0..0..1..0....1..1..1..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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