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%I #15 May 16 2018 11:20:02
%S 8,52,168,380,724,1236,1940,2872,4068,5552,7360,9528,12080,15052,
%T 18480,22388,26812,31788,37340,43504,50316,57800,65992,74928,84632,
%U 95140,106488,118700,131812,145860,160868,176872,193908,212000,231184,251496
%N Number of -n..n arrays x(0..3) of 4 elements with zero sum and no two neighbors equal.
%C Row 4 of A199704.
%H R. H. Hardin, <a href="/A199706/b199706.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 3*a(n-1)-3*a(n-2)+2*a(n-3)-3*a(n-4)+3*a(n-5)-a(n-6).
%F Empirical g.f.: 4*x*(2 + 7*x + 9*x^2 + 4*x^3 + 2*x^4) / ((1 - x)^4*(1 + x + x^2)). - _Colin Barker_, May 16 2018
%e Some solutions for n=5:
%e ..3...-3....3....2....2....2....2...-5...-2...-3....2....0....4...-3....4...-5
%e ..0...-5...-3...-4....1...-1...-1....5...-4....3....0...-2...-4...-2...-3....3
%e .-3....3...-4...-2...-5....4....0....3....1....5....2...-3...-1....1...-4....4
%e ..0....5....4....4....2...-5...-1...-3....5...-5...-4....5....1....4....3...-2
%Y Cf. A199704.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 09 2011
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