%I #8 Jan 25 2019 08:28:57
%S 8,62,222,572,1220,2298,3962,6392,9792,14390,20438,28212,38012,50162,
%T 65010,82928,104312,129582,159182,193580,233268,278762,330602,389352,
%U 455600,529958,613062,705572,808172,921570,1046498,1183712,1333992
%N Number of length-4 0..n arrays with no repeated value differing from the previous repeated value by one or less.
%H R. H. Hardin, <a href="/A269607/b269607.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = n^4 + 4*n^3 + 4*n^2 - n.
%F Conjectures from _Colin Barker_, Jan 25 2019: (Start)
%F G.f.: 2*x*(4 + 11*x - 4*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=7:
%e ..0. .7. .6. .5. .4. .1. .1. .5. .3. .5. .0. .3. .1. .3. .4. .4
%e ..5. .6. .4. .1. .0. .2. .4. .1. .4. .1. .3. .0. .7. .0. .6. .3
%e ..3. .5. .6. .7. .6. .1. .6. .7. .3. .7. .4. .3. .0. .6. .0. .7
%e ..7. .7. .6. .5. .1. .4. .2. .4. .2. .6. .7. .4. .1. .7. .1. .7
%Y Row 4 of A269606.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 01 2016