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%I #7 Jul 19 2018 09:49:51
%S 24,76,192,456,1046,2408,5458,12624,28762,67278,154580,365720,847122,
%T 2024242,4721206,11375392,26680354,64720018,152478042,371900846,
%U 879299028,2154128424,5107422788,12556963016,29839050584,73573746366
%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 six distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211574/b211574.txt">Table of n, a(n) for n = 1..41</a>
%F Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 46*a(n-3) + 88*a(n-4) + 49*a(n-5) - 231*a(n-6) + 82*a(n-7) + 168*a(n-8) - 100*a(n-9) - 36*a(n-10) + 24*a(n-11).
%F Empirical g.f.: 2*x*(12 - 34*x - 96*x^2 + 318*x^3 + 135*x^4 - 766*x^5 + 24*x^6 + 634*x^7 - 72*x^8 - 144*x^9 + 24*x^10) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 6*x^2)*(1 - 2*x - x^2 + x^3)). - _Colin Barker_, Jul 19 2018
%e Some solutions for n=5:
%e ..1....1....0...-2...-1....0....1...-1....0....1....2...-1...-1....0....2....1
%e ..0....0....1...-1...-1...-2....0...-2...-1....0....1....0...-1....2...-1...-2
%e ..1....1....2....0...-1...-1....1....1....0...-1....0...-1...-1....2....0....1
%e ..1...-2....2...-1....1...-2....1....0...-1....0....1...-1...-2....2...-1...-2
%e ..1....1....2...-2....1....0....2....1...-1....1....2...-2...-2....2...-2....1
%e ..2....0....2...-2...-1...-2....2....2....0....2....0...-1...-1....0....1....2
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 16 2012
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