Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

A146047

Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =13a(5) =19a(6) =471a(7) =1011a(8) =17363a(9) =51133a(10) =4227773a(11) =17426251a(12) =4189737457a(13) =23548416611

External references