A191478 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 2 king-move neighboring 1s

2, 7, 28, 231, 3022, 63851, 2254102, 129926375, 12346854981, 1930513304865, 496013097993148, 209682700667891310, 145774046555290357339, 166670977286765976049136, 313418443881609705847873703

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..20

Example

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

Crossrefs

Sequence in context: A123026 A013011 A013181 * A321181 A122118 A337429

Adjacent sequences: A191475 A191476 A191477 * A191479 A191480 A191481

Keyword

nonn

Author

R. H. Hardin Jun 03 2011

Status

approved