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=3, one peak.
FORMULA
Empirical: a(n) = 3*a(n-1) -3*a(n-2) +4*a(n-3) -a(n-4) +a(n-5).
Empirical: G.f.: -x*(1+3*x^2+x^4)/(-1+3*x-3*x^2+4*x^3-x^4+x^5). - R. J. Mathar, Jul 09 2017
EXAMPLE
Some solutions for n=5
..2....2....1....0....2....2....0....1....0....1....1....0....2....1....0....2
..2....2....1....1....2....2....2....1....2....2....1....0....2....2....1....2
..0....1....1....2....0....2....2....0....2....2....1....1....1....2....1....0
..0....1....1....2....1....1....2....0....0....0....2....1....2....2....2....2
..0....0....1....2....1....1....1....0....0....0....2....1....2....0....2....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 25 2011
STATUS
approved