|
%I #8 Jul 19 2018 16:39:26
%S 36,50,72,114,184,316,544,972,1728,3144,5680,10424,18992,35008,64080,
%T 118400,217296,402032,738960,1368240,2517136,4662736,8582416,15902160,
%U 29278992,54258576,99918352,185180816,341049872,632107792,1164231696
%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 four distinct values for every i,j,k<=n.
%H R. H. Hardin, <a href="/A211720/b211720.txt">Table of n, a(n) for n = 1..60</a>
%F Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 10*a(n-4) + 10*a(n-5) + 4*a(n-6) - 4*a(n-7).
%F Empirical g.f.: 2*x*(18 + 7*x - 97*x^2 - 21*x^3 + 149*x^4 + 10*x^5 - 58*x^6) / ((1 - x)*(1 - 2*x^2)*(1 - 4*x^2 + 2*x^4)). - _Colin Barker_, Jul 19 2018
%e Some solutions for n=5:
%e .-2....0....3....2....0...-3...-1....0....2....1...-2...-2...-2....0...-2...-3
%e .-1...-3....2...-1...-1...-1...-2...-3....3....0...-1...-1...-3....3...-1...-2
%e ..0....0....1....2...-2...-3...-1....0....2...-1....0....0...-2....0...-2...-3
%e ..1....3....0...-1...-3...-1...-2....3....1....0...-1....1...-1....3...-1...-2
%e ..0....0....1....2...-2...-3...-1....0....2....1....0....2...-2....0....0...-1
%e ..1...-3....0...-1...-1...-1....0....3....3....2....1....1...-3....3...-1...-2
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 20 2012
|
