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A207421
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Number of nX3 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 0 vertically
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2
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6, 36, 114, 351, 1162, 3633, 11067, 33994, 103972, 315900, 959469, 2913192, 8833205, 26769585, 81116398, 245729000, 744251550, 2253989395, 6825832650, 20669704173, 62589261963, 189520870122, 573861525576, 1737611142984, 5261327251049
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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) -4*a(n-2) +13*a(n-3) -30*a(n-4) +3*a(n-5) -29*a(n-6) +50*a(n-7) +56*a(n-8) +28*a(n-9) -34*a(n-10) -76*a(n-11) -42*a(n-12) +14*a(n-13) +35*a(n-14) +20*a(n-15) +4*a(n-16) -7*a(n-17) -2*a(n-18) -a(n-19) -a(n-20)
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EXAMPLE
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Some solutions for n=4
..1..0..0....0..0..1....1..1..1....1..1..0....1..1..0....0..0..1....0..0..1
..0..0..1....0..0..1....1..1..1....0..0..1....1..0..1....1..0..0....0..1..1
..1..0..1....0..0..1....1..1..1....1..1..1....1..0..1....1..0..1....0..1..1
..1..0..1....0..0..1....1..1..1....1..1..0....0..0..1....0..0..1....0..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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