A191294 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 1 knight-move neighboring 1

1, 1, 3, 7, 21, 122, 880, 6953, 72647, 1129137, 24364420, 694152879, 24831611879, 1208655194306, 80157177796753, 7105061448777651

Offset

1,3

Links

Table of n, a(n) for n=1..16.

Example

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

Crossrefs

Sequence in context: A031885 A259202 A169981 * A177820 A174230 A158236

Adjacent sequences: A191291 A191292 A191293 * A191295 A191296 A191297

Keyword

nonn

Author

R. H. Hardin May 29 2011

Status

approved