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Number of length n+2 0..6 arrays with no pair in any consecutive three terms totalling exactly 6.
1

%I #7 Nov 06 2018 04:12:40

%S 216,1116,5766,29790,153906,795144,4108062,21223992,109652160,

%T 566509902,2926831878,15121261374,78122885724,403616150730,

%U 2085253182384,10773307330236,55659500700198,287560720444278,1485661331645130

%N Number of length n+2 0..6 arrays with no pair in any consecutive three terms totalling exactly 6.

%H R. H. Hardin, <a href="/A245993/b245993.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) + a(n-2) + 25*a(n-3) + 5*a(n-4).

%F Empirical g.f.: 6*x*(36 + 42*x + 181*x^2 + 35*x^3) / (1 - 4*x - x^2 - 25*x^3 - 5*x^4). - _Colin Barker_, Nov 06 2018

%e Some solutions for n=5:

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

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

%e ..3....6....2....4....1....2....2....0....5....2....4....1....4....6....6....6

%e ..2....1....1....3....3....1....1....2....2....2....0....4....3....2....6....4

%e ..1....6....1....5....0....0....3....1....0....3....5....4....4....5....3....3

%e ..3....3....4....0....4....2....4....2....2....2....2....6....5....3....1....1

%e ..4....1....4....2....1....3....1....6....2....6....0....3....4....2....6....0

%Y Column 6 of A245995.

%K nonn

%O 1,1

%A _R. H. Hardin_, Aug 09 2014