A191603 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 4 horizontally, vertically or diagonally neighboring 1s

2, 8, 58, 856, 24368, 1348666, 145634012, 30602076600, 12521664597022, 9976791553569412, 15477885230123717308, 46755695360925385415444, 275015972447150661617296526, 3149789884136909401259248638902

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..18

Example

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

Crossrefs

Sequence in context: A256034 A086907 A132186 * A162068 A162069 A162070

Adjacent sequences: A191600 A191601 A191602 * A191604 A191605 A191606

Keyword

nonn

Author

R. H. Hardin Jun 08 2011

Status

approved