cp's OEIS Frontend

A199911 Number of -n..n arrays x(0..3) of 4 elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).

%I A199911 #9 May 17 2018 08:39:17
%S A199911 8,24,72,152,256,448,680,952,1384,1848,2368,3136,3912,4760,5960,7128,
%T A199911 8384,10112,11752,13496,15848,18040,20352,23424,26248,29208,33096,
%U A199911 36632,40320,45120,49448,53944,59752,64952,70336,77248,83400,89752,97864
%N A199911 Number of -n..n arrays x(0..3) of 4 elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).
%C A199911 Row 4 of A199909.
%H A199911 R. H. Hardin, <a href="/A199911/b199911.txt">Table of n, a(n) for n = 1..200</a>
%F A199911 Empirical: a(n) = a(n-1) +3*a(n-3) -3*a(n-4) -3*a(n-6) +3*a(n-7) +a(n-9) -a(n-10).
%F A199911 Empirical g.f.: 8*x*(1 + x)*(1 + x^2)*(1 + x + 4*x^2 + x^3 + x^4) / ((1 - x)^4*(1 + x + x^2)^3). - _Colin Barker_, May 17 2018
%e A199911 Some solutions for n=6:
%e A199911 ..0....0....0....2...-4...-5....1...-4...-4...-1...-3....5...-6....3....4....0
%e A199911 .-5....4....1...-3....3....0....2....3....6....0...-4...-5....1...-5....5...-2
%e A199911 ..3...-3....5...-2....1....5...-5...-2....4...-2....6...-1....3....6...-5...-1
%e A199911 ..2...-1...-6....3....0....0....2....3...-6....3....1....1....2...-4...-4....3
%Y A199911 Cf. A199909.
%K A199911 nonn
%O A199911 1,1
%A A199911 _R. H. Hardin_, Nov 11 2011