login
Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a 1 X 5 or 5 X 1 block.
0

%I #6 Nov 25 2018 23:42:03

%S 1,1,1,1,1,1,2,1,3,1,6,1,15,3,43,8,140,27,656,89,3196,333,18641,1310,

%T 125685,7293,1010276,48975,9527791,401989

%N Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a 1 X 5 or 5 X 1 block.

%e Maximal 9 X 9 example:

%e 0 0 0 0 0 0 0 0 0

%e 0 0 1 1 1 1 1 0 0

%e 0 1 0 0 0 0 0 1 0

%e 0 1 0 0 0 0 0 1 0

%e 0 1 0 0 0 0 0 1 0

%e 0 1 0 0 0 0 0 1 0

%e 0 1 0 0 0 0 0 1 0

%e 0 0 1 1 1 1 1 0 0

%e 0 0 0 0 0 0 0 0 0

%K nonn

%O 1,7

%A _R. H. Hardin_, Oct 25 2008