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A200834 Number of 0..4 arrays x(0..n+1) of n+2 elements without any two consecutive increases or two consecutive decreases. 1
105, 435, 1817, 7587, 31677, 132263, 552247, 2305835, 9627715, 40199277, 167846875, 700822891, 2926195229, 12217949255, 51014464969, 213004292437, 889371840403, 3713456951747, 15505058633553, 64739364520389 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 4 of A200838.
LINKS
FORMULA
Empirical: a(n) = 5*a(n-1) -4*a(n-2) +3*a(n-3) -3*a(n-4) +a(n-5) -a(n-6).
Empirical g.f.: x*(105 - 90*x + 62*x^2 - 73*x^3 + 20*x^4 - 25*x^5) / ((1 - x)*(1 - 4*x - 3*x^3 - x^5)). - Colin Barker, Oct 14 2017
EXAMPLE
Some solutions for n=3
..2....4....1....2....3....1....1....1....0....2....4....2....0....1....1....3
..2....3....4....0....0....4....0....2....4....2....4....4....4....1....4....1
..2....3....4....0....2....3....1....2....3....2....1....4....3....3....3....1
..3....4....0....4....1....4....0....1....4....2....3....1....4....2....3....1
..3....3....1....0....2....2....0....2....3....0....1....2....2....4....4....0
CROSSREFS
Sequence in context: A165056 A165060 A165069 * A143041 A078420 A152826
KEYWORD
nonn
AUTHOR
R. H. Hardin Nov 23 2011
STATUS
approved

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Last modified February 27 08:19 EST 2024. Contains 370367 sequences. (Running on oeis4.)