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A191691
Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 E, SE or S neighboring 1
1
2, 6, 32, 294, 4640, 125338, 5802288, 459958324, 62453890000, 14523496866976, 5784570667981520, 3945961499388113436, 4610186764537663968556, 9225021921428355206788506, 31615478219055162849230486428
OFFSET
1,1
LINKS
EXAMPLE
Some solutions for n=5
..0..1..0..0..1....0..0..0..1..0....1..0..1..0..0....1..0..1..0..1
..1..1..0..0..1....0..1..0..0..1....0..0..0..1..0....0..0..1..0..1
..0..0..0..0..1....0..0..1..0..0....1..0..0..0..0....1..1..0..0..0
..0..0..0..0..0....1..0..0..0..0....0..1..0..0..1....0..0..0..1..0
..1..1..1..0..0....0..1..0..0..1....0..0..0..1..0....1..1..0..0..0
CROSSREFS
Sequence in context: A346270 A133596 A088437 * A191712 A277475 A277484
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 11 2011
STATUS
approved