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A250374
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Number of length 1+6 0..n arrays with every seven consecutive terms having the maximum of some three terms equal to the minimum of the remaining four terms.
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1
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93, 1382, 8964, 37385, 118621, 312578, 720112, 1498569, 2879845, 5190966, 8877188, 14527617, 22903349, 34968130, 51921536, 75234673, 106688397, 148414054, 202936740, 273221081, 362719533, 475423202, 615915184, 789426425, 1001894101
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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) = (7/2)*n^6 + 14*n^5 + (105/4)*n^4 + (161/6)*n^3 + (63/4)*n^2 + (17/3)*n + 1.
G.f.: x*(93 + 731*x + 1243*x^2 + 404*x^3 + 55*x^4 - 7*x^5 + x^6) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
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EXAMPLE
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Some solutions for n=5:
..0....3....3....1....1....2....1....3....3....2....3....4....3....1....0....4
..5....4....5....5....3....0....1....1....3....4....3....2....3....5....3....4
..2....5....1....2....1....0....5....0....1....5....3....5....3....0....1....4
..1....1....2....3....2....0....0....1....2....3....3....5....5....3....1....2
..0....0....1....2....0....4....3....1....1....0....3....2....0....3....4....3
..1....1....5....1....4....4....0....5....2....3....2....0....4....5....1....0
..3....0....2....2....0....0....2....5....5....3....3....2....2....3....1....3
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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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