A146686 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1100-1000-1111 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 3, 7, 15, 31, 63, 167, 435, 1337, 5021, 19355, 85901, 388093, 1971221, 10932161

Offset

1,8

Links

Table of n, a(n) for n=1..21.

Example

Maximal 8 X 8 example
.0.0.0.1.1.1.1.0
.0.0.0.1.0.0.0.1
.0.0.0.1.1.0.0.1
.1.1.1.0.0.1.0.1
.1.0.1.0.0.1.1.1
.1.0.0.1.1.0.0.0
.1.0.0.0.1.0.0.0
.0.1.1.1.1.0.0.0

Crossrefs

Sequence in context: A325920 A351754 A174743 * A309172 A178459 A129984

Adjacent sequences: A146683 A146684 A146685 * A146687 A146688 A146689

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved