OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
T. Mansour and M. Shattuck, Counting Peaks and Valleys in a Partition of a Set, J. Int. Seq. 13 (2010), 10.6.8, Lemma 2.1, k=4, no peak.
FORMULA
Empirical: a(n) = 4*a(n-1) -6*a(n-2) +10*a(n-3) -5*a(n-4) +6*a(n-5) -a(n-6) +a(n-7).
Empirical: G.f.: -x*(1+6*x^2+5*x^4+x^6) / (-1+4*x-6*x^2+10*x^3-5*x^4+6*x^5-x^6+x^7). - R. J. Mathar, May 17 2014
EXAMPLE
Some solutions for n=5
..3....1....1....1....1....3....3....1....0....1....1....3....2....0....3....3
..3....1....1....2....2....3....3....1....2....1....1....3....2....2....3....3
..1....3....1....2....3....3....1....0....3....0....2....3....3....3....3....0
..3....3....2....1....3....3....3....0....3....0....2....3....3....3....2....1
..3....0....2....0....3....0....3....0....0....0....1....0....1....3....1....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 29 2011
STATUS
approved