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%I #9 Jan 24 2019 17:07:33
%S 3,9,24,62,154,376,902,2142,5040,11786,27418,63544,146822,338478,
%T 778944,1790282,4110730,9432424,21633542,49603134,113717328,260691722,
%U 597649402,1370287384,3142264070,7206988878,16533117792,37935980618,87065571946
%N Number of length-n 0..2 arrays with no repeated value differing from the previous repeated value by one or less.
%H R. H. Hardin, <a href="/A269601/b269601.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 5*a(n-1) - 5*a(n-2) - 8*a(n-3) + 12*a(n-4).
%F Empirical g.f.: x*(3 - 6*x - 6*x^2 + 11*x^3) / ((1 - 2*x)^2*(1 - x - 3*x^2)). - _Colin Barker_, Jan 24 2019
%e Some solutions for n=7:
%e ..2. .2. .2. .2. .2. .0. .1. .0. .2. .2. .2. .1. .0. .1. .2. .2
%e ..1. .1. .1. .1. .0. .2. .2. .2. .0. .0. .1. .2. .2. .2. .0. .1
%e ..2. .1. .0. .2. .2. .1. .1. .2. .0. .1. .0. .2. .1. .1. .1. .0
%e ..0. .2. .2. .1. .1. .0. .1. .1. .2. .1. .1. .0. .0. .0. .0. .1
%e ..1. .1. .0. .0. .0. .2. .2. .0. .0. .0. .0. .1. .2. .1. .1. .2
%e ..1. .0. .1. .2. .2. .0. .0. .2. .1. .1. .0. .2. .1. .0. .0. .1
%e ..2. .1. .0. .0. .1. .0. .1. .0. .2. .2. .2. .0. .1. .2. .1. .0
%Y Column 2 of A269606.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 01 2016
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