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A192325
Half the number of n X n symmetric binary matrices with no element both equal to all its immediate N and W neighbors if they exist and unequal to all its immediate E and S neighbors if they exist
1
1, 0, 2, 16, 244, 6938, 371342, 37280140, 7016898676, 2476338996046, 1638683680332022, 2033288154472125378, 4730646433644468299754, 20637618504497727985203276, 168817037972490215464239418020
OFFSET
1,3
LINKS
EXAMPLE
Some solutions for 4X4 with a(1,1)=0
..0..0..0..1....0..0..0..0....0..0..0..0....0..0..1..0....0..0..1..0
..0..1..0..1....0..1..1..0....0..1..0..0....0..0..0..0....0..0..0..1
..0..0..1..0....0..1..0..1....0..0..1..0....1..0..1..0....1..0..0..0
..1..1..0..1....0..0..1..0....0..0..0..1....0..0..0..1....0..1..0..1
CROSSREFS
Sequence in context: A217813 A217814 A217815 * A009233 A188560 A012462
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 28 2011
STATUS
approved