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A245866 Number of length n+2 0..5 arrays with some pair in every consecutive three terms totalling exactly 5. 1

%I #11 Nov 05 2018 03:05:06

%S 90,318,960,3102,9726,30900,97602,309078,977664,3094038,9789654,

%T 30977796,98020170,310161870,981426624,3105480558,9826505742,

%U 31093507092,98387556594,311322635814,985101990912,3117106968486,9863299264806

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

%H R. H. Hardin, <a href="/A245866/b245866.txt">Table of n, a(n) for n = 1..210</a>

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

%F 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 Some solutions for n=7:

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

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

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

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

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

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

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

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

%e 2 5 2 2 3 1 5 3 4 3 5 3 1 5 2 1

%Y Column 5 of A245869.

%K nonn

%O 1,1

%A _R. H. Hardin_, Aug 04 2014

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Last modified March 29 06:57 EDT 2024. Contains 371265 sequences. (Running on oeis4.)