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A248457 Number of length n+2 0..4 arrays with no three consecutive terms having the sum of any two elements equal to twice the third.

%I A248457 #8 Nov 08 2018 19:08:49
%S A248457 96,380,1512,6040,24160,96736,387488,1552448,6220480,24926080,
%T A248457 99883840,400260160,1603955712,6427525312,25757039296,103216337152,
%U A248457 413619611968,1657501354048,6642119813120,26617026736320,106662654436544
%N A248457 Number of length n+2 0..4 arrays with no three consecutive terms having the sum of any two elements equal to twice the third.
%H A248457 R. H. Hardin, <a href="/A248457/b248457.txt">Table of n, a(n) for n = 1..210</a>
%F A248457 Empirical: a(n) = 3*a(n-1) + 5*a(n-2) + 2*a(n-3) - 16*a(n-4) - 28*a(n-5) - 8*a(n-6).
%F A248457 Empirical g.f.: 4*x*(24 + 23*x - 27*x^2 - 147*x^3 - 186*x^4 - 50*x^5) / ((1 - 2*x)*(1 - x - 7*x^2 - 16*x^3 - 16*x^4 - 4*x^5)). - _Colin Barker_, Nov 08 2018
%e A248457 Some solutions for n=6:
%e A248457 ..1....0....0....2....3....3....0....0....3....2....3....1....3....4....0....1
%e A248457 ..3....4....1....0....4....4....3....1....1....3....2....4....2....1....3....3
%e A248457 ..0....1....3....3....4....3....4....1....0....0....2....2....2....4....0....0
%e A248457 ..0....4....4....1....3....0....0....0....3....4....3....2....3....4....2....0
%e A248457 ..2....1....3....4....1....4....1....4....0....1....2....0....3....0....3....1
%e A248457 ..3....0....0....3....1....0....3....4....2....2....0....0....1....0....0....1
%e A248457 ..0....1....2....1....2....0....4....2....2....4....0....4....3....4....2....3
%e A248457 ..0....0....0....0....4....4....3....2....3....1....3....4....3....3....3....1
%Y A248457 Column 4 of A248461.
%K A248457 nonn
%O A248457 1,1
%A A248457 _R. H. Hardin_, Oct 06 2014