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%I #8 Jul 19 2018 09:50:01
%S 16,44,108,260,604,1436,3324,7964,18556,44924,105468,257660,608764,
%T 1497596,3555324,8790524,20940796,51959804,124076028,308619260,
%U 738172924,1839144956,4403888124,10984562684,26322698236,65706098684,157533601788
%N Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having four or six distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211573/b211573.txt">Table of n, a(n) for n = 1..72</a>
%F Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 24*a(n-3) + 4*a(n-4) + 36*a(n-5) - 24*a(n-6).
%F Empirical g.f.: 4*x*(4 - x - 30*x^2 + 14*x^3 + 42*x^4 - 24*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 6*x^2)). - _Colin Barker_, Jul 19 2018
%e Some solutions for n=5:
%e ..0....0....1...-1....0....1...-1....2....0....1...-1....1....2...-1...-2....0
%e ..1....1....2....2....1....2...-2....1....1....2...-2...-2....1....2...-1...-1
%e ..2....2...-1....1....2....0....1....2...-2....0....1....1...-2...-1....2....2
%e .-1....0...-2....2....1....2....0....1...-1....1....2....0....1...-2...-1....1
%e ..2....2....1....1...-2....0....1...-2...-2....0....1...-1....2....1...-2...-2
%e ..1....0....0....0...-1....1....2...-1....1....1...-2....0....1....0....1....1
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 16 2012