A199904 Number of -3..3 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).

1, 4, 24, 72, 256, 1312, 5206, 21208, 97668, 422052, 1819620, 8158144, 36110122, 159422584, 712790438, 3182921756, 14206099012, 63688577860, 285783359204, 1282956672032, 5770687400200, 25983122754016, 117074268243396

Offset: 1

Author

R. H. Hardin Nov 11 2011

Keywords

• nonn

Comments

Column 3 of A199909

Examples

			Some solutions for n=6
.-2....2...-1...-1....1...-2...-1...-2...-3...-3....2....2....2....3...-3...-1
..3...-3....1....0...-3...-1....1....2....2...-1....0....1...-3...-1....2...-2
.-2....1....2...-2....1....0...-1....1....1....3....2...-1....1...-3...-3...-3
..2....3....3....0....3....2....0...-3....0...-1...-3...-3...-3...-2....1....2
.-3...-2...-2....1...-2....1....1....2...-2....0...-1....1....1....2....2....3
..2...-1...-3....2....0....0....0....0....2....2....0....0....2....1....1....1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200