%I #8 Jan 25 2019 08:28:36
%S 4,16,64,249,954,3611,13544,50442,186822,688899,2531406,9275757,
%T 33912330,123759252,450985950,1641487455,5969001906,21688869249,
%U 78760649178,285872602590,1037218320720,3762161399673,13642773106086,49463937282915
%N Number of length-n 0..3 arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.
%H R. H. Hardin, <a href="/A269614/b269614.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 12*a(n-1) - 51*a(n-2) + 81*a(n-3) - 3*a(n-4) - 63*a(n-5) - 24*a(n-6) - 9*a(n-7).
%F Empirical g.f.: x*(4 - 32*x + 76*x^2 - 27*x^3 - 54*x^4 - 22*x^5 - 7*x^6) / ((1 - 3*x)*(1 - 9*x + 24*x^2 - 9*x^3 - 24*x^4 - 9*x^5 - 3*x^6)). - _Colin Barker_, Jan 25 2019
%e Some solutions for n=8:
%e ..0. .3. .2. .3. .1. .0. .0. .0. .2. .2. .2. .3. .2. .2. .2. .3
%e ..3. .3. .1. .3. .3. .2. .2. .2. .0. .3. .1. .1. .1. .3. .2. .0
%e ..3. .0. .3. .2. .2. .1. .0. .3. .1. .3. .3. .3. .2. .0. .2. .0
%e ..2. .3. .2. .2. .1. .3. .0. .3. .0. .1. .2. .2. .1. .0. .1. .2
%e ..3. .2. .3. .2. .0. .2. .1. .0. .1. .0. .0. .3. .3. .1. .3. .0
%e ..1. .2. .3. .1. .0. .3. .2. .3. .3. .3. .0. .2. .1. .2. .1. .2
%e ..0. .1. .0. .3. .3. .3. .0. .2. .0. .3. .2. .3. .2. .0. .0. .0
%e ..3. .0. .2. .0. .1. .1. .2. .3. .2. .1. .3. .3. .1. .0. .3. .1
%Y Column 3 of A269619.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 01 2016