A191551 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 diagonally or antidiagonally neighboring 1

2, 8, 33, 297, 4032, 91392, 3461143, 214272233, 22066261672, 3754762272000, 1054824912314030, 490291568481195135, 376674319103188012304, 478415094920126210097672, 1004588343161199901448153154

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..26

Example

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

Crossrefs

Sequence in context: A236382 A269890 A005040 * A263627 A172448 A268601

Adjacent sequences: A191548 A191549 A191550 * A191552 A191553 A191554

Keyword

nonn

Author

R. H. Hardin Jun 05 2011

Status

approved