A202040 Number of zero-sum n X n -1..1 arrays with every element unequal to at most two horizontal and vertical neighbors

1, 19, 415, 31753, 6221993, 3573771563

Offset

1,2

Comments

Diagonal of A202047

Links

Table of n, a(n) for n=1..6.

Example

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

Crossrefs

Sequence in context: A252927 A172740 A172816 * A244765 A069612 A077716

Adjacent sequences: A202037 A202038 A202039 * A202041 A202042 A202043

Keyword

nonn

Author

R. H. Hardin Dec 10 2011

Status

approved