A145779 Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally.

1, 1, 1, 4, 8, 17, 58, 224, 939, 4970, 30996, 225413, 1970184, 20575972, 252185309, 3690646219, 64088665934, 1323737025941, 32350145726565, 942783467265088, 32507076170340916, 1335377761740727698, 64933573760903971267

Offset

1,4

Links

Table of n, a(n) for n=1..23.

Crossrefs

Sequence in context: A335274 A296399 A119471 * A252790 A144178 A075558

Adjacent sequences: A145776 A145777 A145778 * A145780 A145781 A145782

Keyword

nonn

Author

R. H. Hardin, Oct 18 2008

Status

approved