A146001 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 3 X 3 plus 2,1 2,2 2,3 1,2 3,2.

1, 1, 2, 1, 4, 3, 13, 10, 51, 49, 310, 338, 2482, 3185, 28263, 43203, 449926, 801916, 9914815, 21045123, 308205077, 768844389, 13283687618, 39245465846, 803638667971, 2803939636958, 67770861551303, 279412729196042

Offset

1,3

Links

Table of n, a(n) for n=1..28.

Example

Maximal 8 X 8 example
.0.0.0.0.0.0.1.0
.0.0.1.0.0.1.1.1
.0.1.1.1.0.0.1.0
.0.0.1.0.0.0.0.0
.0.0.0.0.0.1.0.0
.0.1.0.0.1.1.1.0
.1.1.1.0.0.1.0.0
.0.1.0.0.0.0.0.0

Crossrefs

Sequence in context: A138509 A099331 A260319 * A091879 A036069 A338846

Adjacent sequences: A145998 A145999 A146000 * A146002 A146003 A146004

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved