A199825 Number of -1..1 arrays x(0..n+1) of n+2 elements with zero sum and no two neighbors summing to zero.

2, 4, 4, 10, 22, 34, 66, 138, 250, 472, 944, 1806, 3450, 6772, 13172, 25478, 49794, 97348, 189772, 371246, 727506, 1424586, 2793034, 5483342, 10766950, 21154424, 41599648, 81840866, 161080918, 317230034, 625030514, 1231964394, 2429323642

Offset: 1

Author

R. H. Hardin Nov 11 2011

Keywords

• nonn

Comments

Column 1 of A199832

Examples

			All solutions for n=3
.-1....0....0....1
.-1....1...-1....1
..0....0....0....0
..1...-1....1...-1
..1....0....0...-1
		

Links

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