A191224 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 3 king-move neighboring 1s

1, 2, 3, 4, 10, 29, 74, 267, 1270, 6853, 46338, 452697, 5888876, 103743236, 2568916974, 83100685126, 3548166614885, 196909507948313, 14058252177537760

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Example

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

Crossrefs

Sequence in context: A123700 A005433 A139009 * A359995 A272523 A337536

Adjacent sequences: A191221 A191222 A191223 * A191225 A191226 A191227

Keyword

nonn

Author

R. H. Hardin May 27 2011

Status

approved