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Number of -n..n arrays x(0..4) of 5 elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).
1

%I #8 May 17 2018 08:29:32

%S 14,82,256,804,1836,3196,6064,10276,14846,23154,34096,44912,63114,

%T 85670,106780,140664,181052,217516,274204,339976,397866,485814,585856,

%U 672256,801254,945786,1068792,1249964,1450540,1619260,1865064,2134572,2359126

%N Number of -n..n arrays x(0..4) of 5 elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).

%C Row 5 of A199909.

%H R. H. Hardin, <a href="/A199912/b199912.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = a(n-1) +4*a(n-3) -4*a(n-4) -6*a(n-6) +6*a(n-7) +4*a(n-9) -4*a(n-10) -a(n-12) +a(n-13).

%F Empirical g.f.: 2*x*(7 + 34*x + 87*x^2 + 246*x^3 + 380*x^4 + 332*x^5 + 380*x^6 + 246*x^7 + 87*x^8 + 34*x^9 + 7*x^10) / ((1 - x)^5*(1 + x + x^2)^4). - _Colin Barker_, May 17 2018

%e Some solutions for n=6:

%e .-1....4....5....0....2....4...-1...-5....3...-5...-5....0...-6....3....1...-2

%e ..4...-6...-5....2....4...-6...-6....5....2....5....2...-4....4....5....3....6

%e .-1....4....3....0...-4...-1....5....6...-5....4....3....3...-3....0...-2....1

%e ..3...-3...-2...-2...-5...-2....6...-4....5...-6...-1...-5....5...-2....0...-3

%e .-5....1...-1....0....3....5...-4...-2...-5....2....1....6....0...-6...-2...-2

%Y Cf. A199909.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 11 2011