cp's OEIS Frontend

A199912 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).

%I A199912 #8 May 17 2018 08:29:32
%S A199912 14,82,256,804,1836,3196,6064,10276,14846,23154,34096,44912,63114,
%T A199912 85670,106780,140664,181052,217516,274204,339976,397866,485814,585856,
%U A199912 672256,801254,945786,1068792,1249964,1450540,1619260,1865064,2134572,2359126
%N A199912 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 A199912 Row 5 of A199909.
%H A199912 R. H. Hardin, <a href="/A199912/b199912.txt">Table of n, a(n) for n = 1..200</a>
%F A199912 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 A199912 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 A199912 Some solutions for n=6:
%e A199912 .-1....4....5....0....2....4...-1...-5....3...-5...-5....0...-6....3....1...-2
%e A199912 ..4...-6...-5....2....4...-6...-6....5....2....5....2...-4....4....5....3....6
%e A199912 .-1....4....3....0...-4...-1....5....6...-5....4....3....3...-3....0...-2....1
%e A199912 ..3...-3...-2...-2...-5...-2....6...-4....5...-6...-1...-5....5...-2....0...-3
%e A199912 .-5....1...-1....0....3....5...-4...-2...-5....2....1....6....0...-6...-2...-2
%Y A199912 Cf. A199909.
%K A199912 nonn
%O A199912 1,1
%A A199912 _R. H. Hardin_, Nov 11 2011