A145970 - OEIS

A145970

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

%I #6 Feb 25 2023 18:07:05

%S 1,1,1,1,1,1,4,7,15,33,90,201,647,1861,7123,23236,101280,390759,

%T 2050696,9515925,59455120,328131409,2431442671,15797747304,

%U 137926288897,1064505557777

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

%e Maximal 8 X 8 example:

%e 0 0 0 0 0 0 1 0

%e 1 1 1 1 1 0 1 0

%e 0 0 0 0 0 0 1 0

%e 0 1 0 0 0 0 1 0

%e 0 1 0 0 0 0 0 0

%e 0 1 0 1 1 1 1 1

%e 0 1 0 0 0 0 0 0

%K nonn

%O 1,7

%A _R. H. Hardin_, Oct 25 2008