A145959 - OEIS

A145959

Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.

%I #3 Mar 31 2012 12:35:08

%S 1,1,1,5,17,75,405,2821,26895,365651,6440881,149278281,4554728635,

%T 183204987539,9796495036771,702723336742467

%N Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.

%e Maximal 8 X 8 example

%e .0.1.1.0.0.0.1.0

%e .1.1.0.0.1.0.1.1

%e .0.0.0.1.1.0.0.1

%e .1.1.0.1.0.1.1.0

%e .0.1.1.0.1.0.1.1

%e .1.0.0.1.1.0.0.0

%e .1.1.0.1.0.0.1.1

%e .0.1.0.0.0.1.1.0

%K nonn

%O 1,4

%A _R. H. Hardin_, Oct 25 2008