A191650 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 1 antidiagonally neighboring 1.

1, 2, 4, 8, 32, 192, 1728, 25920, 518400, 14515200, 609638400, 36578304000, 3292047360000, 444426393600000, 86663146752000000, 24785659971072000000, 10360405867908096000000, 6299126767688122368000000

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..51

Example

Some solutions for n=5:
..0..0..0..0..0....0..1..0..0..0....0..1..0..0..1....0..1..0..0..0
..0..0..1..0..0....1..0..1..0..0....1..0..1..1..0....1..0..1..0..0
..0..1..0..1..0....0..1..0..1..0....0..1..0..1..0....0..1..0..1..0
..0..0..1..0..0....0..0..1..0..1....0..1..1..0..1....0..0..1..0..0
..0..0..0..0..0....0..0..0..1..0....1..0..0..1..0....0..0..0..0..0

Crossrefs

Sequence in context: A186340 A228920 A064378 * A036544 A094334 A138744

Adjacent sequences: A191647 A191648 A191649 * A191651 A191652 A191653

Keyword

nonn

Author

R. H. Hardin, Jun 10 2011

Status

approved