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Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.
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%I #6 Nov 26 2018 17:05:27

%S 1,1,1,1,1,1,1,1,3,3,9,9,23,23,125,125,821,821,6239,6239,71403,71403,

%T 1048093,1048093,19913069,19913069,517074745,517074745,17642361171,

%U 17642361171

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

%e Maximal 9 X 9 example:

%e 0 0 1 0 0 0 1 0 0

%e 0 0 1 1 0 1 1 0 0

%e 1 1 0 1 0 1 0 1 1

%e 0 1 1 0 0 0 1 1 0

%e 0 0 0 0 0 0 0 0 0

%e 0 1 1 0 0 0 1 1 0

%e 1 1 0 1 0 1 0 1 1

%e 0 0 1 1 0 1 1 0 0

%e 0 0 1 0 0 0 1 0 0

%K nonn

%O 1,9

%A _R. H. Hardin_, Oct 25 2008