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A207896
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Number of 3 X n 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 0 and 1 1 1 vertically.
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1
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6, 36, 84, 198, 462, 1080, 2520, 5886, 13746, 32100, 74964, 175062, 408822, 954720, 2229552, 5206662, 12159090, 28395060, 66310836, 154855350, 361632894, 844519416, 1972201800, 4605672606, 10755603282, 25117504404, 58656777396
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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) + 2*a(n-2) + 2*a(n-3) + a(n-4) + a(n-5) for n>6.
Empirical g.f.: 6*x*(1 + 5*x + 6*x^2 + 5*x^3 + 3*x^4 + 2*x^5) / (1 - x - 2*x^2 - 2*x^3 - x^4 - x^5). - Colin Barker, Jun 26 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..0..0....0..1..1..0....1..1..1..1....1..1..1..0....0..0..1..1
..0..1..1..0....0..0..1..0....1..1..0..0....1..0..0..1....0..1..0..0
..1..0..0..1....1..0..0..1....0..0..1..1....0..1..0..0....1..1..0..0
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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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