A201885 Number of zero-sum nX2 -2..2 arrays with every element equal to at least one horizontal or vertical neighbor

1, 9, 63, 413, 3293, 25123, 196811, 1610765, 13183301, 109772649, 924269015, 7845330131, 67157103399, 578601709251, 5012862231269, 43640547493913, 381459159995789, 3345900096556721, 29435197443234979, 259612374333413841

Offset

1,2

Comments

Column 2 of A201888

Links

R. H. Hardin, Table of n, a(n) for n = 1..128

Example

Some solutions for n=6
.-1.-1...-1.-1....0..0...-1.-1...-1.-1....1..1...-1..2....0..0....0..2....1..1
..1.-2...-1..0....2..0....0..0....0..0....1..0...-1..2...-1..2....0..2...-1.-1
..1.-2...-1..0....2..0...-1..0....0..0....0..0....1..1...-1..2...-1.-1....0.-1
..0..0....2..2...-1.-1...-1..2....0..0...-1..0...-2.-2....0..0...-1..0....0..1
..0..0...-2.-2....0..0....0..2....2.-1...-1..0....2.-2....0.-1...-1..0....1..1
..2..2....2..2...-1.-1....0..0....2.-1...-1..0....2.-2....0.-1....0..0...-1.-1

Crossrefs

Sequence in context: A016137 A230547 A339786 * A225964 A037508 A037691

Adjacent sequences: A201882 A201883 A201884 * A201886 A201887 A201888

Keyword

nonn

Author

R. H. Hardin Dec 06 2011

Status

approved