A145929 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation.

1, 1, 1, 1, 2, 3, 8, 13, 44, 111, 556, 1606, 9677, 40103, 359014, 1871694, 20359902, 143317291, 2226693360, 20614186256, 404517634279, 4951846403553, 133436650402934, 2175520025174634, 76183950538555436, 1636466403191913572

Offset

1,5

Links

Table of n, a(n) for n=1..26.

Example

Maximal 8 X 8 example
.0.0.0.0.0.0.0.0
.0.0.0.1.1.1.0.0
.0.0.0.0.1.0.1.0
.0.1.0.0.0.1.1.0
.0.1.1.0.0.0.1.0
.0.1.0.1.0.0.0.0
.0.0.1.1.1.0.0.0
.0.0.0.0.0.0.0.0

Crossrefs

Sequence in context: A025575 A077055 A327868 * A153865 A369774 A331820

Adjacent sequences: A145926 A145927 A145928 * A145930 A145931 A145932

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved