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Number of length-n 0..5 arrays with no repeated value differing from the previous repeated value by more than one.
1

%I #7 Jan 24 2019 11:44:55

%S 6,36,216,1276,7456,43184,248324,1419502,8074172,45734140,258127540,

%T 1452448400,8151217700,45640705908,255046211478,1422758512212,

%U 7924694792032,44081166810484,244913122501544,1359313355233592

%N Number of length-n 0..5 arrays with no repeated value differing from the previous repeated value by more than one.

%H R. H. Hardin, <a href="/A269580/b269580.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 20*a(n-1) - 146*a(n-2) + 440*a(n-3) - 328*a(n-4) - 470*a(n-5) - 76*a(n-6) + 5*a(n-7).

%F Empirical g.f.: 2*x*(3 - 42*x + 186*x^2 - 214*x^3 - 200*x^4 - 26*x^5 + 2*x^6) / ((1 - 5*x)*(1 - 15*x + 71*x^2 - 85*x^3 - 97*x^4 - 15*x^5 + x^6)). - _Colin Barker_, Jan 24 2019

%e Some solutions for n=6:

%e ..3. .0. .4. .2. .1. .0. .5. .4. .0. .5. .5. .3. .4. .0. .0. .4

%e ..5. .4. .2. .3. .4. .5. .2. .0. .1. .4. .5. .0. .5. .4. .0. .3

%e ..1. .1. .5. .4. .1. .5. .1. .2. .0. .2. .2. .1. .2. .1. .1. .2

%e ..3. .0. .1. .2. .4. .2. .2. .1. .4. .1. .1. .1. .3. .5. .2. .1

%e ..4. .1. .0. .4. .5. .0. .0. .3. .5. .5. .3. .3. .4. .3. .1. .0

%e ..4. .3. .3. .2. .0. .2. .5. .0. .5. .1. .4. .2. .3. .3. .2. .3

%Y Column 5 of A269583.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 01 2016