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.

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.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =1a(7) =3a(8) =2a(9) =5a(10) =6a(11) =12a(12) =20a(13) =34a(14) =68a(15) =154a(16) =265a(17) =709a(18) =1281a(19) =3847a(20) =8603a(21) =25073a(22) =71217a(23) =206107a(24) =695670a(25) =2185029a(26) =7989257a(27) =27851353a(28) =111404338a(29) =424685942

External references