A201841 Number of zero-sum nX2 -1..1 arrays with every element equal to at least one horizontal or vertical neighbor

1, 5, 25, 97, 411, 1897, 8741, 41689, 201985, 987407, 4891069, 24457873, 123131033, 623695509, 3174983801, 16227954653, 83226630287, 428047598133, 2206766393985, 11399915802567, 58993096946055, 305739808201773, 1586610751415691

Offset

1,2

Comments

Column 2 of A201847

Links

R. H. Hardin, Table of n, a(n) for n = 1..95

Example

Some solutions for n=8
.-1.-1...-1..0....1.-1....1..1....1..1...-1..0...-1.-1...-1.-1...-1.-1...-1..0
..1..1...-1..0....1.-1....1.-1....1..0...-1..0....0.-1....1..1...-1.-1...-1..0
..0..1....1..1....1..0....1.-1...-1..0....0..1....0..1....0..1....0..1....0..0
..0..1...-1.-1...-1..0...-1.-1...-1..1....0..1....0..1....0..1....0..1....0..0
.-1..1....1.-1...-1..0....1..1...-1..1....0..0....1..1....0..0....0..0...-1..1
.-1..1....1..1....1..0....0..0....0..0...-1.-1...-1..1....0.-1...-1..1...-1..1
..0.-1....1.-1....1.-1...-1.-1....0..0....0..1...-1..0....0.-1...-1..1....0..0
..0.-1....1.-1....1.-1....0..0...-1.-1....0..1....0..0....0..0....1..1....1..1

Crossrefs

Sequence in context: A223945 A197085 A273747 * A146830 A316778 A255612

Adjacent sequences: A201838 A201839 A201840 * A201842 A201843 A201844

Keyword

nonn

Author

R. H. Hardin Dec 06 2011

Status

approved