A146928 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 1001-1111-1001 pattern in any orientation.

1, 1, 1, 1, 1, 1, 3, 7, 13, 26, 70, 233, 869, 3436, 14680, 71757, 413520, 2721699, 19996282, 163378650, 1508376980, 15870814986, 189905190363, 2566140210269, 39033535389467, 670295254576489, 13033170011033515, 287051699463343610

Offset

1,7

Links

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

Example

Maximal 8 X 8 example
.0.0.0.0.0.0.0.0
.0.0.0.0.1.0.0.1
.0.0.0.0.1.1.1.1
.0.0.0.0.1.0.0.1
.0.1.1.1.0.0.0.0
.0.0.1.0.0.0.0.0
.0.0.1.0.0.0.0.0
.0.1.1.1.0.0.0.0

Crossrefs

Sequence in context: A284297 A205521 A125898 * A068673 A298360 A140465

Adjacent sequences: A146925 A146926 A146927 * A146929 A146930 A146931

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved