A146148 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation.

1, 1, 1, 3, 5, 7, 25, 61, 137, 491, 1895, 6799, 35271, 188161, 1045823, 6942831, 54475785, 429190219, 4220050567, 45840848045, 555820995851, 7424820570827, 118936859724455, 2001479983540325, 39919686781316217, 873987056828886899

Offset

1,4

Links

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

Example

Maximal 8 X 8 example
.0.0.1.0.0.1.1.0
.0.1.1.0.0.0.1.1
.1.1.0.1.1.0.0.1
.0.0.1.0.1.1.0.0
.0.0.1.1.0.1.0.0
.1.0.0.1.1.0.1.1
.1.1.0.0.0.1.1.0
.0.1.1.0.0.1.0.0

Crossrefs

Sequence in context: A108313 A045966 A374670 * A098475 A131039 A362684

Adjacent sequences: A146145 A146146 A146147 * A146149 A146150 A146151

Keyword

nonn

Author

R. H. Hardin, Oct 27 2008

Status

approved