A202041 Number of zero-sum nX2 -1..1 arrays with every element unequal to at most two horizontal and vertical neighbors

3, 19, 73, 335, 1593, 7669, 37311, 184335, 919889, 4620477, 23332387, 118371541, 602858159, 3080279011, 15782030681, 81053501795, 417143999201, 2150782607289, 11107401645291, 57445755808701, 297487456185331, 1542374070100235

Offset

1,1

Comments

Column 2 of A202047

Links

R. H. Hardin, Table of n, a(n) for n = 1..93

Example

Some solutions for n=7
..0..1....0..1...-1.-1....1..0...-1..0...-1..0....1.-1....1..1...-1..1....1..1
.-1.-1....1..1...-1.-1....0..0....1..0....1..1...-1..1...-1..1...-1..0....0.-1
..1..1....0..0....1.-1...-1.-1....1..0...-1.-1...-1..1...-1..1...-1..0....0.-1
..0..0....0..0....1..0....1..1....1..0....1.-1...-1..0....1..1....0..0....1..1
..1.-1....0.-1....1..0....0..1...-1.-1....1.-1....0..0...-1.-1....0..1....1.-1
..1.-1...-1.-1....1..1....0..0...-1.-1....1.-1....0..0...-1.-1....0..1...-1.-1
.-1..0....0..0....0..0...-1.-1....1..1....0..1....0..1....0..0...-1..1....0..0

Crossrefs

Sequence in context: A090698 A350713 A215802 * A245507 A247059 A243142

Adjacent sequences: A202038 A202039 A202040 * A202042 A202043 A202044

Keyword

nonn

Author

R. H. Hardin Dec 10 2011

Status

approved