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%I #8 Nov 01 2018 11:39:01
%S 13,35,97,271,757,2115,5913,16535,46237,129291,361537,1010975,2827013,
%T 7905235,22105577,61814311,172852717,483351835,1351607313,3779529135,
%U 10568780117,29553711331,82641690297,231092768695,646209770813
%N Number of length n+3 0..2 arrays with no four elements in a row with pattern aabb (with a!=b) and new values 0..2 introduced in 0..2 order.
%H R. H. Hardin, <a href="/A242578/b242578.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + 6*a(n-3) - 4*a(n-4).
%F Empirical g.f.: x*(13 - 17*x + 22*x^2 - 20*x^3) / ((1 - x)*(1 - 3*x + 2*x^2 - 4*x^3)). - _Colin Barker_, Nov 01 2018
%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....0....0....0....1....0....1....1....1....1....0....1....1....0....1
%e ..1....2....1....1....1....0....0....2....0....1....1....1....1....0....1....1
%e ..2....1....0....0....0....2....1....1....1....2....0....2....2....0....2....2
%e ..1....0....2....0....1....0....0....1....0....0....1....1....1....2....0....1
%e ..2....2....1....0....0....2....0....1....2....2....2....1....2....1....2....0
%e ..1....1....1....0....1....2....1....1....0....1....0....2....1....0....2....2
%Y Column 2 of A242584.
%K nonn
%O 1,1
%A _R. H. Hardin_, May 17 2014
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