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A268940 Number of length-n 0..4 arrays with no repeated value unequal to the previous repeated value plus one mod 4+1. 1

%I

%S 5,25,120,565,2615,11950,54045,242365,1079240,4777225,21038595,

%T 92244790,402898865,1753806625,7611458520,32945585965,142262759615,

%U 612991045150,2636186279445,11317111447765,48506655275240,207603081203425

%N Number of length-n 0..4 arrays with no repeated value unequal to the previous repeated value plus one mod 4+1.

%H R. H. Hardin, <a href="/A268940/b268940.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 7*a(n-1) - 7*a(n-2) - 20*a(n-3).

%F Empirical g.f.: 5*x*(1 - 2*x - 4*x^2) / ((1 - 4*x)*(1 - 3*x - 5*x^2)). - _Colin Barker_, Jan 17 2019

%e Some solutions for n=7:

%e ..2. .0. .3. .2. .2. .4. .1. .2. .3. .2. .2. .1. .1. .1. .3. .2

%e ..3. .4. .3. .1. .3. .0. .3. .1. .3. .4. .0. .0. .2. .4. .0. .1

%e ..1. .3. .0. .3. .2. .3. .1. .3. .2. .4. .3. .1. .4. .1. .2. .1

%e ..3. .4. .1. .1. .0. .4. .4. .1. .1. .3. .2. .2. .1. .1. .1. .4

%e ..4. .0. .4. .4. .0. .0. .1. .4. .4. .4. .0. .2. .2. .4. .4. .1

%e ..0. .0. .0. .0. .1. .2. .3. .3. .1. .3. .4. .4. .4. .0. .2. .4

%e ..1. .3. .2. .1. .4. .3. .4. .3. .4. .0. .1. .0. .0. .2. .2. .0

%Y Column 4 of A268944.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 16 2016

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Last modified October 26 05:34 EDT 2021. Contains 348256 sequences. (Running on oeis4.)