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%I #8 Jul 20 2018 06:02:12
%S 48,82,140,250,448,824,1520,2852,5364,10208,19464,37428,72080,139688,
%T 271012,528328,1030776,2018668,3955520,7774312,15285508,30128648,
%U 59399624,117351116,231876816,458968664,908552868,1801178616,3570988568
%N Number of -3..3 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 or four distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211722/b211722.txt">Table of n, a(n) for n = 1..58</a>
%F Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - 25*a(n-3) + 16*a(n-4) + 46*a(n-5) - 48*a(n-6) - 26*a(n-7) + 36*a(n-8) + 4*a(n-9) - 8*a(n-10).
%F Empirical g.f.: 2*x*(24 - 55*x - 142*x^2 + 363*x^3 + 225*x^4 - 744*x^5 - 65*x^6 + 534*x^7 - 14*x^8 - 124*x^9) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 4*x^2 + 2*x^4)). - _Colin Barker_, Jul 20 2018
%e Some solutions for n=5:
%e .-1...-1...-3...-3....0...-3...-1....3...-2....1...-2...-2....1....0...-3....2
%e .-1...-1....1...-3...-3...-3....0....3...-1....1....1...-1....2...-1....3....1
%e .-1....2...-3....3....0...-3....1...-3....0...-1....1....0....1....0...-3....0
%e .-1...-1....1....3...-3...-3....2...-3....1....1...-2....1....0...-1...-3...-1
%e ..1...-1...-3....3....0...-3....1....3....2....1....1....2...-1....0...-3....0
%e .-1....2....1....3....3....3....0....3....1...-1....1....3....0....1...-3...-1
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 20 2012
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