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A249963
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Number of length 3+5 0..n arrays with no six consecutive terms having the maximum of any two terms equal to the minimum of the remaining four terms.
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1
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15, 897, 14094, 111746, 585069, 2319123, 7532380, 21069828, 52478667, 119135973, 250738026, 495501318, 928465577, 1662329463, 2861289912, 4758396424, 7676971911, 12056692041, 18484955334, 27734216586, 40805996517, 58982320859
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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) = n^8 + (152/105)*n^7 + (62/15)*n^6 + (26/5)*n^5 + (1/2)*n^4 + (19/15)*n^3 + (28/15)*n^2 - (29/70)*n.
G.f.: x*(15 + 762*x + 6561*x^2 + 15932*x^3 + 13281*x^4 + 3594*x^5 + 175*x^6) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>9.
(End)
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EXAMPLE
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Some solutions for n=4:
..4....1....4....0....1....4....3....3....1....3....3....0....2....2....0....1
..4....1....3....2....3....1....2....4....4....1....2....2....2....0....2....1
..0....0....0....3....0....0....3....0....0....2....0....4....3....0....2....0
..0....1....0....3....2....4....3....0....0....0....3....0....3....4....0....3
..4....2....4....1....1....0....0....2....3....1....1....1....3....4....4....0
..2....0....1....3....0....1....4....3....1....0....0....3....3....4....4....3
..4....2....3....1....1....2....0....4....1....3....4....4....0....4....1....4
..1....1....4....2....2....3....3....3....1....1....2....4....2....3....0....4
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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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