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A254702
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Number of length 4+4 0..n arrays with every five consecutive terms having the maximum of some two terms equal to the minimum of the remaining three terms.
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1
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86, 1140, 6808, 26759, 81390, 208114, 469376, 962541, 1831798, 3282224, 5596152, 9151987, 14445614, 22114542, 32964928, 48001625, 68461398, 95849452, 131979416, 179016927, 239526958, 316525034, 413532480, 534635845, 684550646, 868689576
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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) = (1/35)*n^7 + (8/5)*n^6 + (56/5)*n^5 + 25*n^4 + (249/10)*n^3 + (77/5)*n^2 + (481/70)*n + 1.
G.f.: x*(86 + 452*x + 96*x^2 - 601*x^3 + 122*x^4 - 18*x^5 + 8*x^6 - x^7) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.
(End)
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EXAMPLE
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Some solutions for n=5:
..3....1....3....0....2....1....0....4....4....4....4....3....4....2....0....3
..3....0....2....4....3....5....5....1....0....5....1....1....0....2....4....3
..3....0....2....2....0....4....1....0....0....3....2....1....4....1....3....5
..5....0....3....2....5....3....5....1....0....3....1....0....0....0....0....3
..3....5....2....3....2....3....1....1....5....3....1....3....0....1....0....3
..3....3....2....1....2....1....0....1....0....3....3....1....0....3....0....3
..1....0....2....2....3....3....1....4....0....0....0....1....2....1....0....4
..5....0....4....4....0....4....2....2....1....5....2....3....1....2....0....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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