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A245866 Number of length n+2 0..5 arrays with some pair in every consecutive three terms totalling exactly 5.

%I A245866 #11 Nov 05 2018 03:05:06
%S A245866 90,318,960,3102,9726,30900,97602,309078,977664,3094038,9789654,
%T A245866 30977796,98020170,310161870,981426624,3105480558,9826505742,
%U A245866 31093507092,98387556594,311322635814,985101990912,3117106968486,9863299264806
%N A245866 Number of length n+2 0..5 arrays with some pair in every consecutive three terms totalling exactly 5.
%H A245866 R. H. Hardin, <a href="/A245866/b245866.txt">Table of n, a(n) for n = 1..210</a>
%F A245866 Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - a(n-3).
%F A245866 Empirical g.f.: 6*x*(15 + 23*x - 6*x^2) / (1 - 2*x - 4*x^2 + x^3). - _Colin Barker_, Nov 04 2018
%e A245866 Some solutions for n=7:
%e A245866   1   5   0   3   5   3   2   3   0   4   3   4   1   0   1   3
%e A245866   5   4   3   1   2   0   2   4   1   0   2   1   4   2   0   0
%e A245866   0   1   2   4   3   2   3   1   4   5   0   5   2   3   5   5
%e A245866   2   0   3   5   3   5   4   5   0   0   3   0   1   1   0   0
%e A245866   3   4   2   0   2   0   1   0   1   5   2   4   3   2   1   2
%e A245866   2   5   3   5   1   5   4   0   4   3   4   1   2   3   4   5
%e A245866   0   0   4   0   4   4   4   5   1   2   1   4   4   0   3   0
%e A245866   5   4   1   3   1   0   1   2   0   0   4   1   3   5   1   4
%e A245866   2   5   2   2   3   1   5   3   4   3   5   3   1   5   2   1
%Y A245866 Column 5 of A245869.
%K A245866 nonn
%O A245866 1,1
%A A245866 _R. H. Hardin_, Aug 04 2014