Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a T-shape (1,1), (1,2), (1,3), (2,2) in any orientation.
A145931
Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a T-shape (1,1), (1,2), (1,3), (2,2) in any orientation.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =7a(6) =22a(7) =31a(8) =166a(9) =409a(10) =2848a(11) =8224a(12) =74341a(13) =301687a(14) =3626272a(15) =18878730a(16) =299451324a(17) =2103168465a(18) =44919780098a(19) =414592933018
External references
- oeis: A145931