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%I #7 Mar 21 2018 11:42:38
%S 3,9,24,63,159,396,969,2349,5640,13455,31911,75348,177225,415557,
%T 971808,2267631,5281359,12280860,28518153,66147165,153274488,
%U 354861711,820976631,1898144676,4386240393,10131006069,23390390544,53984735343
%N Number of length-n 0..2 arrays with no repeated value unequal to the previous repeated value plus one mod 2+1.
%C Column 2 of A268944.
%H R. H. Hardin, <a href="/A268938/b268938.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) + a(n-2) - 6*a(n-3).
%F Empirical g.f.: 3*x*(1 - 2*x^2) / ((1 - 2*x)*(1 - x - 3*x^2)). - _Colin Barker_, Mar 21 2018
%e Some solutions for n=9:
%e ..0. .1. .2. .2. .2. .1. .2. .2. .0. .2. .1. .0. .0. .0. .0. .1
%e ..0. .2. .0. .1. .1. .0. .0. .0. .1. .1. .2. .2. .2. .2. .2. .0
%e ..2. .0. .2. .2. .2. .1. .1. .1. .0. .0. .1. .1. .0. .0. .0. .0
%e ..1. .2. .2. .0. .0. .0. .2. .1. .1. .0. .0. .2. .1. .0. .2. .2
%e ..0. .0. .0. .2. .0. .1. .0. .2. .0. .1. .0. .1. .0. .2. .0. .1
%e ..1. .2. .2. .2. .2. .1. .2. .1. .1. .1. .2. .0. .0. .0. .0. .1
%e ..0. .1. .0. .0. .0. .0. .1. .0. .2. .0. .0. .1. .1. .1. .2. .2
%e ..1. .0. .0. .2. .2. .2. .1. .2. .1. .2. .1. .2. .1. .1. .1. .2
%e ..2. .2. .2. .1. .1. .0. .0. .2. .2. .1. .0. .1. .0. .2. .2. .1
%Y Cf. A268944.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 16 2016
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