A269636 - OEIS

%I #7 Jan 25 2019 09:28:41

%S 5,25,120,567,2637,12125,55225,249600,1120868,5006144,22255415,

%T 98544130,434827380,1912861067,8392454605,36733957588,160447861687,

%U 699496998228,3044446874255,13230474539089,57418454111103,248881927670961

%N Number of length-n 0..4 arrays with no repeated value differing from the previous repeated value by other than plus two or minus 1.

%H R. H. Hardin, <a href="/A269636/b269636.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 13*a(n-1) - 51*a(n-2) + 15*a(n-3) + 240*a(n-4) - 96*a(n-5) - 509*a(n-6) - 268*a(n-7).

%F Empirical g.f.: x*(5 - 40*x + 50*x^2 + 207*x^3 - 189*x^4 - 559*x^5 - 273*x^6) / ((1 - 4*x)*(1 - 9*x + 15*x^2 + 45*x^3 - 60*x^4 - 144*x^5 - 67*x^6)). - _Colin Barker_, Jan 25 2019

%e Some solutions for n=7:

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

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

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

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

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

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

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

%Y Column 4 of A269640.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 02 2016