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A190657
Half the number of n X n symmetric binary matrices with no element unequal to a strict majority of its diagonal, vertical and horizontal neighbors.
0
1, 1, 3, 10, 42, 244, 2031, 22714, 342292, 6943430, 188479666, 6843502049, 331910774405, 21483424837024, 1854744805774187, 213498320443922663, 32758157589935274374
OFFSET
1,3
EXAMPLE
Some solutions for n=5 with a(1,1)=0:
..0..0..1..1..1....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0
..0..0..0..1..1....0..1..1..1..0....0..0..0..1..1....0..1..1..0..0
..1..0..0..0..0....0..1..1..1..1....0..0..1..1..1....0..1..1..1..1
..1..1..0..0..0....0..1..1..1..1....0..1..1..1..1....0..0..1..1..1
..1..1..0..0..0....0..0..1..1..1....0..1..1..1..1....0..0..1..1..1
CROSSREFS
Sequence in context: A232606 A334270 A185621 * A143523 A288813 A306237
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 16 2011
STATUS
approved