A146139 - OEIS

A146139

Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 5-point barb 1,1 1,2 2,2 2,3 3,2 in any orientation.

%I #3 Mar 31 2012 12:35:09

%S 1,1,1,1,7,21,61,403,3415,36395,473261,8291363,204964495,6738662861,

%T 291876652529,16526293766701,1250870357604441,127503882340930419,

%U 17331789387120484429,3122597067315836972733,746394914944854757141353

%N Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 5-point barb 1,1 1,2 2,2 2,3 3,2 in any orientation.

%e Maximal 8 X 8 example

%e .0.0.1.1.0.1.1.0

%e .0.0.0.1.1.0.1.1

%e .1.0.0.1.0.0.1.0

%e .1.1.1.0.0.0.0.1

%e .0.1.0.0.0.1.1.1

%e .1.0.0.0.1.0.1.0

%e .1.1.1.0.1.1.0.0

%e .0.1.0.1.1.0.0.0

%K nonn

%O 1,5

%A _R. H. Hardin_, Oct 27 2008