A145776 Number of n X n binary arrays symmetric about main diagonal with all ones connected only either two adjacent vertically or two adjacent horizontally.

1, 1, 3, 8, 30, 185, 1496, 16722, 271203, 6203100, 197367854, 8915141875, 569403889486, 51067273219036, 6465618290035839, 1155799498602804735, 291067895373206126374, 103368821914100007066399

Offset

1,3

Links

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

Crossrefs

Sequence in context: A274934 A066304 A298456 * A379905 A066165 A323775

Adjacent sequences: A145773 A145774 A145775 * A145777 A145778 A145779

Keyword

nonn

Author

R. H. Hardin, Oct 18 2008

Status

approved