A146009 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 3X3 tee 1,1 1,2 1,3 2,2 3,2 in any orientation.

1, 1, 1, 1, 3, 9, 22, 75, 380, 2417, 17011, 150387, 1725197, 24767029, 439881987, 9753623996, 269467512241, 9272282447537, 399403152426578, 21537582386961680, 1447800106086744192, 121198502960515093107

Offset

1,5

Links

Table of n, a(n) for n=1..22.

Example

Maximal 8 X 8 example
.0.0.1.1.1.0.0.0
.0.0.0.1.0.0.0.0
.1.0.0.1.0.0.0.0
.1.1.1.0.0.0.0.1
.1.0.0.0.0.1.1.1
.0.0.0.0.1.0.0.1
.0.0.0.0.1.0.0.0
.0.0.0.1.1.1.0.0

Crossrefs

Sequence in context: A296582 A203454 A197666 * A326007 A272559 A270991

Adjacent sequences: A146006 A146007 A146008 * A146010 A146011 A146012

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved