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%I #8 Jul 19 2018 08:23:01
%S 24,52,94,174,304,552,980,1802,3286,6158,11512,21948,41836,80838,
%T 156278,304946,595408,1169984,2300260,4542522,8974198,17784654,
%U 35255336,70043180,139186780,277026950,551453398,1099000626,2190431680,4369469520
%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 two, four or five distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211569/b211569.txt">Table of n, a(n) for n = 1..64</a>
%F Empirical: a(n) = 4*a(n-1) + a(n-2) - 21*a(n-3) + 16*a(n-4) + 29*a(n-5) - 34*a(n-6) - 6*a(n-7) + 12*a(n-8).
%F Empirical g.f.: 2*x*(12 - 22*x - 69*x^2 + 125*x^3 + 111*x^4 - 196*x^5 - 37*x^6 + 58*x^7) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 3*x^2)). - _Colin Barker_, Jul 19 2018
%e Some solutions for n=5.
%e .-2....2....2....0...-1....1....2...-1....1...-1....2...-1....2...-2...-2...-2
%e .-2....1...-2...-1...-2...-1....1....0...-2....1...-2...-1....0....2...-2....1
%e .-2....0....2....0...-1....1....0...-1....1...-1....2...-1....2....2...-2...-2
%e .-2...-1....2...-1....0....1....1....0...-2...-1....0....1....0....2...-2...-2
%e .-2....0....2....0....1....1....2...-1...-2....1....2....1....2...-2...-2....1
%e .-2...-1....2....1....0....1....1...-2...-2....1....0....1...-2...-2....2...-2
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 16 2012