A242543 - OEIS

%I #6 May 18 2014 11:06:17

%S 12,32,88,242,660,1800,4920,13448,36736,100352,274176,749088,2046528,

%T 5591168,15275392,41733248,114017280,311500800,851036160,2325074432,

%U 6352221184,17354590208,47413622784,129536428032,353900101632

%N Number of length n+3 0..2 arrays with no four elements in a row with pattern aabb (possibly a=b) and new values 0..2 introduced in 0..2 order

%C Column 2 of A242549

%H R. H. Hardin, <a href="/A242543/b242543.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) +4*a(n-3) +4*a(n-4).

%F Empirical: G.f.: -2*x*(6+4*x+12*x^2+9*x^3) / ( (2*x^2+2*x-1)*(2*x^2+1) ). - _R. J. Mathar_, May 18 2014

%e Some solutions for n=4

%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

%e ..0....1....1....1....1....1....1....1....0....0....1....1....0....0....1....1

%e ..1....1....0....2....0....0....1....1....0....1....0....0....1....1....0....0

%e ..2....1....0....1....0....2....2....0....1....2....0....2....0....0....1....2

%e ..1....2....0....0....2....0....0....1....2....0....1....0....0....0....0....1

%e ..1....1....1....1....0....1....2....0....2....0....2....0....0....2....0....1

%e ..0....2....0....2....1....1....0....0....1....1....1....1....1....1....0....2

%K nonn

%O 1,1

%A _R. H. Hardin_, May 17 2014