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A207400
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Number of n X 5 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.
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1
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12, 144, 612, 1782, 4212, 8692, 16284, 28362, 46652, 73272, 110772, 162174, 231012, 321372, 437932, 586002, 771564, 1001312, 1282692, 1623942, 2034132, 2523204, 3102012, 3782362, 4577052, 5499912, 6565844, 7790862, 9192132, 10788012
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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) = (1/3)*n^5 + 3*n^4 + (28/3)*n^3 + 7*n^2 - (29/3)*n + 2.
G.f.: 2*x*(6 + 36*x - 36*x^2 + 15*x^3 - x^5) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
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EXAMPLE
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Some solutions for n=4:
..0..0..0..0..0....1..0..1..0..1....1..1..0..1..0....0..1..0..1..0
..0..1..0..0..0....0..1..0..0..0....0..0..0..0..0....0..1..0..0..0
..0..0..0..0..0....0..1..0..0..0....1..1..0..0..0....0..1..0..0..0
..0..0..0..0..0....0..1..0..0..0....1..1..0..0..0....0..1..0..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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