A201955 Number of zero-sum n X 2 -3..3 arrays with every element unequal to at most two horizontal and vertical neighbors.

7, 231, 1587, 17903, 194633, 2232183, 25952953, 305979795, 3640250461, 43624267941, 525774918227, 6366440653727, 77388201173481, 943784967491137, 11542145313593503, 141498452574240619, 1738344524754583621

Offset: 1

Author

R. H. Hardin, Dec 06 2011

Keywords

• nonn

Comments

Column 2 of A201958.

Examples

			Some solutions for n=4
..2..3...-3.-3...-2.-3...-2..3...-2..1....2.-3....2.-3....2..0...-3.-1....1.-2
..0..0....2..2....1..1....0..0...-2..0....1..1....3.-3....0.-1....3..0....0..0
.-2.-2...-1.-1....2..2....1..1....2..0....0..0....3..0....0.-1....3..0....0..0
.-2..1....3..1....0.-1...-1.-2....2.-1...-1..0...-2..0....3.-3...-2..0....3.-2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..68

Crossrefs

Cf. A201958.