%I #8 Jan 25 2019 08:28:12
%S 15,78,249,612,1275,2370,4053,6504,9927,14550,20625,28428,38259,50442,
%T 65325,83280,104703,130014,159657,194100,233835,279378,331269,390072,
%U 456375,530790,613953,706524,809187,922650,1047645,1184928,1335279
%N Number of length-4 0..n 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="/A269620/b269620.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = n^4 + 4*n^3 + 5*n^2 + 5*n.
%F Conjectures from _Colin Barker_, Jan 25 2019: (Start)
%F G.f.: 3*x*(5 + x + 3*x^2 - x^3) / (1 - x)^5.
%F a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
%F (End)
%e Some solutions for n=8:
%e ..2. .5. .6. .8. .5. .2. .1. .4. .1. .5. .5. .6. .0. .5. .7. .2
%e ..2. .7. .2. .7. .2. .2. .0. .6. .0. .1. .6. .0. .3. .6. .1. .5
%e ..6. .5. .7. .0. .2. .3. .6. .7. .0. .5. .1. .2. .5. .2. .7. .2
%e ..3. .2. .6. .0. .5. .8. .0. .6. .7. .6. .2. .2. .4. .4. .2. .4
%Y Row 4 of A269619.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 01 2016
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