A191600 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 horizontally, vertically or diagonally neighboring 1

2, 5, 23, 159, 1646, 28059, 724310, 29626607, 1890041732, 188477431884, 29421793928187, 7179932235630885, 2740816166752070599, 1636347059803667113339, 1527949588062203773106011

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..20

Example

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

Crossrefs

Sequence in context: A242227 A032182 A165902 * A343020 A167142 A136731

Adjacent sequences: A191597 A191598 A191599 * A191601 A191602 A191603

Keyword

nonn

Author

R. H. Hardin Jun 08 2011

Status

approved