%I #11 Oct 16 2017 10:08:18
%S 22,51,121,292,704,1691,4059,9749,23422,56268,135166,324692,779977,
%T 1873673,4500958,10812237,25973244,62393157,149881402,360046432,
%U 864906711,2077686532,4991036946,11989513056,28801314179,69186771332
%N Number of 0..2 arrays x(0..n+1) of n+2 elements without any interior element greater than both neighbors.
%C Column 2 of A200886.
%H R. H. Hardin, <a href="/A200880/b200880.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) -3*a(n-2) +4*a(n-3) -a(n-4) +a(n-5).
%F Empirical g.f.: x*(22 - 15*x + 34*x^2 - 6*x^3 + 9*x^4) / (1 - 3*x + 3*x^2 - 4*x^3 + x^4 - x^5). - _Colin Barker_, Oct 16 2017
%e Some solutions for n=3
%e ..2....0....2....0....2....1....2....2....2....1....1....1....0....2....2....1
%e ..0....2....1....0....1....2....2....1....2....2....0....1....0....2....2....2
%e ..1....2....0....2....1....2....0....2....0....2....1....1....1....1....2....2
%e ..1....0....1....2....0....1....1....2....0....2....1....1....1....0....1....1
%e ..0....1....2....0....1....1....1....1....1....2....1....0....1....1....2....2
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 23 2011