A145947 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected in a 3X2 elbow 1,1 1,2 1,3 2,3 in any orientation.

1, 1, 1, 1, 1, 3, 9, 19, 41, 145, 647, 3181, 16339, 99371, 747763, 6609081, 67311501, 786968963, 10964146353, 178363016765, 3416486494947, 75509091003073, 1969327519976023, 59733023396132639, 2140235098426680865

Offset

1,6

Links

Table of n, a(n) for n=1..25.

Example

Maximal 8 X 8 example
.0.0.0.0.1.0.0.0
.0.0.0.0.1.0.0.0
.0.0.0.1.1.0.0.0
.0.0.1.0.0.1.1.1
.1.1.1.0.0.1.0.0
.0.0.0.1.1.0.0.0
.0.0.0.1.0.0.0.0
.0.0.0.1.0.0.0.0

Crossrefs

Sequence in context: A160704 A279673 A146662 * A153084 A285927 A147371

Adjacent sequences: A145944 A145945 A145946 * A145948 A145949 A145950

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved