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A200836 Number of 0..6 arrays x(0..n+1) of n+2 elements without any two consecutive increases or two consecutive decreases. 1
273, 1491, 8239, 45465, 250913, 1384813, 7642875, 42181611, 232803603, 1284861277, 7091249941, 39137163521, 216001069269, 1192126810953, 6579441195743, 36312451033865, 200411259993515, 1106085433196691 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 6 of A200838.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

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

EXAMPLE

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

CROSSREFS

Sequence in context: A157374 A043467 A028530 * A276980 A214220 A029567

Adjacent sequences:  A200833 A200834 A200835 * A200837 A200838 A200839

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 23 2011

STATUS

approved

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Last modified February 21 04:18 EST 2019. Contains 320371 sequences. (Running on oeis4.)