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A200836
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Number of 0..6 arrays x(0..n+1) of n+2 elements without any two consecutive increases or two consecutive decreases.
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1
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273, 1491, 8239, 45465, 250913, 1384813, 7642875, 42181611, 232803603, 1284861277, 7091249941, 39137163521, 216001069269, 1192126810953, 6579441195743, 36312451033865, 200411259993515, 1106085433196691
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OFFSET
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1,1
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COMMENTS
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Column 6 of A200838.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 7*a(n-1) -9*a(n-2) +6*a(n-3) -9*a(n-4) +7*a(n-5) -7*a(n-6) +5*a(n-7) -2*a(n-8) +a(n-9).
Empirical g.f.: x*(273 - 420*x + 259*x^2 - 427*x^3 + 320*x^4 - 319*x^5 + 236*x^6 - 91*x^7 + 49*x^8) / (1 - 7*x + 9*x^2 - 6*x^3 + 9*x^4 - 7*x^5 + 7*x^6 - 5*x^7 + 2*x^8 - x^9). - Colin Barker, Oct 15 2017
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EXAMPLE
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Some solutions for n=3
..2....4....4....4....0....1....2....4....2....5....4....4....5....2....1....3
..1....3....6....3....3....5....5....3....4....2....3....0....0....1....6....5
..4....4....3....6....1....0....4....3....4....2....3....0....1....6....3....0
..3....2....6....2....5....0....4....1....3....2....6....6....0....0....3....3
..4....5....3....5....4....1....6....3....5....3....4....3....6....5....6....3
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CROSSREFS
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Sequence in context: A157374 A043467 A028530 * A276980 A350303 A214220
Adjacent sequences: A200833 A200834 A200835 * A200837 A200838 A200839
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Nov 23 2011
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STATUS
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approved
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