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%I #8 Jul 18 2018 11:49:52
%S 8,18,42,90,192,394,806,1618,3244,6444,12798,25306,50056,98830,195252,
%T 385546,761880,1505776,2978372,5893812,11672100,23128778,45863610,
%U 91000330,180675314,358921836,713425574,1418791694,2822950098,5619290544
%N Number of -1..1 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, three, four or five distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211527/b211527.txt">Table of n, a(n) for n = 1..63</a>
%F Empirical: a(n) = 5*a(n-1) - 4*a(n-2) - 16*a(n-3) + 27*a(n-4) + 8*a(n-5) - 35*a(n-6) + 10*a(n-7) + 10*a(n-8) - 4*a(n-9).
%F Empirical g.f.: 2*x*(4 - 11*x - 8*x^2 + 40*x^3 - 9*x^4 - 42*x^5 + 23*x^6 + 10*x^7 - 6*x^8) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - x - 2*x^2 + x^3)). - _Colin Barker_, Jul 18 2018
%e Some solutions for n=5:
%e .-1....1....1....1...-1...-1....0...-1....0...-1...-1....1...-1...-1....1...-1
%e ..1....1....0...-1....0....1....1....1....1...-1...-1...-1....1....0....1....0
%e .-1...-1....1....0...-1....1...-1....1....0...-1....1....1...-1...-1....1....1
%e ..1....1....0....1....1...-1....1...-1....1....1...-1...-1...-1....0....1...-1
%e .-1...-1...-1...-1....0....0...-1....1....0....1....1....0...-1....1...-1....1
%e .-1....1....1....1...-1...-1....0....1....1...-1....1....1....1...-1....0...-1
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 14 2012
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