A199524 Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no two consecutive zero elements.

1, 4, 18, 72, 320, 1414, 6346, 28766, 131246, 602390, 2777638, 12857572, 59712940, 278096674, 1298309782, 6074112952, 28470828008, 133671581490, 628526085270, 2959291856816, 13950087683416, 65832860408434, 310987879638926

Offset: 1

Author

R. H. Hardin Nov 07 2011

Keywords

• nonn

Comments

Column 2 of A199530

Examples

			Some solutions for n=5
.-1....2....0...-1...-1....1...-2....2....1....1....0....0...-2....0...-1...-1
..0....1...-2....2....2....1....2...-2....0....2...-1....1....1....1....0...-2
.-2...-2....1....2....2....1...-2....2....1...-1...-1....1....2...-2....2....0
..1...-1....0...-2...-1...-2....2....0...-2....0....0...-1....1....2....1....2
..2....0....1...-1...-2...-1....0...-2....0...-2....2...-1...-2...-1...-2....1
		

Links

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