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A243636
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Number of length n+2 0..5 arrays with no three unequal elements in a row and new values 0..5 introduced in 0..5 order.
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1
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4, 9, 21, 51, 127, 324, 844, 2243, 6073, 16736, 46892, 133443, 385277, 1127352, 3339464, 10003395, 30269129, 92422160, 284470820, 881804563, 2750412037, 8625112792, 27174303856, 85960269683, 272856760081, 868664396112
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 9*a(n-1) - 25*a(n-2) + 7*a(n-3) + 64*a(n-4) - 54*a(n-5) - 48*a(n-6) + 32*a(n-7) + 16*a(n-8).
Empirical g.f.: x*(4 - 27*x + 40*x^2 + 59*x^3 - 126*x^4 - 51*x^5 + 80*x^6 + 32*x^7) / ((1 - x)*(1 - 2*x)*(1 - 2*x - x^2)*(1 - 2*x - 2*x^2)*(1 - 2*x - 4*x^2)). - Colin Barker, Nov 02 2018
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EXAMPLE
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Some solutions for n=6:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....0....1....0....1....1....1....1....0....0....1....0....0....0....0....1
..1....0....1....0....1....0....0....1....1....1....1....0....0....1....1....1
..1....0....2....1....1....1....0....2....1....0....1....1....1....1....0....0
..0....0....2....1....2....1....1....1....2....0....1....1....1....2....1....1
..1....0....0....1....2....0....1....2....2....2....1....2....0....2....1....0
..1....1....0....1....2....1....0....2....2....2....0....2....0....3....0....0
..1....1....1....1....3....1....1....2....3....0....1....1....0....2....1....2
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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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