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A207026
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Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically
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2
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6, 36, 90, 252, 624, 1350, 3025, 6256, 12788, 25792, 50630, 99012, 190920, 365041, 694038, 1309524, 2460150, 4599952, 8565768, 15899422, 29415965, 54278252, 99908040, 183482116, 336298170, 615243752, 1123669472, 2049072321, 3731220822
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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) = 3*a(n-1) +a(n-2) -5*a(n-3) -10*a(n-4) +12*a(n-5) +11*a(n-6) +a(n-7) -15*a(n-8) +a(n-9) -7*a(n-10) +3*a(n-11) +3*a(n-12) +9*a(n-13) -4*a(n-14) -2*a(n-16) -a(n-18) +a(n-19)
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EXAMPLE
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Some solutions for n=4
..1..0..0..1....0..1..0..1....0..0..1..0....1..1..1..0....1..1..0..0
..0..1..0..0....0..1..0..1....1..0..1..0....0..0..1..0....1..1..1..1
..0..1..0..0....0..1..0..1....0..0..1..0....0..0..1..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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