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Number of length-5 0..n arrays with no repeated value differing from the previous repeated value by other than plus or minus one modulo n+1.
1

%I #8 Jan 26 2019 11:10:17

%S 14,174,820,2670,6918,15358,30504,55710,95290,154638,240348,360334,

%T 523950,742110,1027408,1394238,1858914,2439790,3157380,4034478,

%U 5096278,6370494,7887480,9680350,11785098,14240718,17089324,20376270,24150270

%N Number of length-5 0..n arrays with no repeated value differing from the previous repeated value by other than plus or minus one modulo n+1.

%H R. H. Hardin, <a href="/A269680/b269680.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = n^5 + 5*n^4 + 4*n^3 + 6*n^2 + 4*n - 2 for n>1.

%F Conjectures from _Colin Barker_, Jan 26 2019: (Start)

%F G.f.: 2*x*(7 + 45*x - 7*x^2 + 40*x^3 - 36*x^4 + 13*x^5 - 2*x^6) / (1 - x)^6.

%F a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>7.

%F (End)

%e Some solutions for n=3:

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

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

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

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

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

%Y Row 5 of A269678.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 03 2016