A191222 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 1 king-move neighboring 1

1, 3, 5, 17, 107, 598, 5688, 77906, 1352347, 34249359, 1204670396, 58155968015, 3946610726739, 371524667930965, 48587161215494423, 8859996760746649440, 2245679398171585663077, 791847513412090215745935

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..24

Example

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

Crossrefs

Sequence in context: A174722 A176131 A087858 * A084723 A288376 A096178

Adjacent sequences: A191219 A191220 A191221 * A191223 A191224 A191225

Keyword

nonn

Author

R. H. Hardin May 27 2011

Status

approved