A191295 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 2 knight-move neighboring 1s.

1, 1, 2, 17, 61, 241, 1077, 10002, 130992, 2166639, 41299118, 1000354787, 34454184106

Offset

1,3

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A071402 A228641 A226417 * A002430 A160469 A176581

Adjacent sequences: A191292 A191293 A191294 * A191296 A191297 A191298

Keyword

nonn

Author

R. H. Hardin, May 29 2011

Status

approved