A191572 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 4 knight-move neighboring 1s

2, 8, 64, 1024, 24975, 1117404, 98925520, 16397607520, 4973951282668, 2743737089908402, 2786025507390606149

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Example

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

Crossrefs

Sequence in context: A153534 A153563 A178169 * A191573 A136283 A139680

Adjacent sequences: A191569 A191570 A191571 * A191573 A191574 A191575

Keyword

nonn

Author

R. H. Hardin Jun 06 2011

Status

approved