A145794 - OEIS

A145794

Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only either four adjacent vertically or four adjacent horizontally.

%I #5 Nov 25 2018 12:23:17

%S 1,1,1,1,1,2,1,3,2,5,6,12,20,34,68,154,265,709,1281,3847,8603,25073,

%T 71217,206107,695670,2185029,7989257,27851353,111404338,424685942

%N Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only either four adjacent vertically or four adjacent horizontally.

%K nonn

%O 1,6

%A _R. H. Hardin_, Oct 19 2008