A145930 - OEIS

A145930

Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation.

%I #5 Nov 25 2018 12:19:52

%S 1,1,1,1,2,1,4,1,10,3,38,10,203,33,1282,134,10692,947,122622,8780,

%T 1931387,97821,38646298,1375312,1027005070,27712816,36128007770,

%U 754977953,1725393598658,26645291289

%N Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation.

%e Maximal 9 X 9 example:

%e 0 1 1 1 0 1 1 1 0

%e 1 0 1 0 1 0 1 0 1

%e 1 1 0 1 1 1 0 1 1

%e 1 0 1 0 0 0 1 0 1

%e 0 1 1 0 0 0 1 1 0

%e 1 0 1 0 0 0 1 0 1

%e 1 1 0 1 1 1 0 1 1

%e 1 0 1 0 1 0 1 0 1

%e 0 1 1 1 0 1 1 1 0

%K nonn

%O 1,5

%A _R. H. Hardin_, Oct 25 2008