A191223 Number of n X n symmetric binary matrices with each 1 adjacent to exactly 2 king-move neighboring 1s

1, 3, 6, 16, 88, 534, 4001, 49783, 802282, 16846980, 518093110, 21604679482, 1210757513851, 95028176738441, 10229389014494032, 1500221649654979714, 303756994018728446946, 84493641616490831589232

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A051271 A028405 A328276 * A301515 A014645 A195996

Adjacent sequences: A191220 A191221 A191222 * A191224 A191225 A191226

Keyword

nonn

Author

R. H. Hardin May 27 2011

Status

approved