Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a 2 X 2 elbow 1,1 1,2 2,1 in any orientation.

A145941

Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a 2 X 2 elbow 1,1 1,2 2,1 in any orientation.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =9a(5) =17a(6) =39a(7) =147a(8) =697a(9) =3223a(10) =21385a(11) =138955a(12) =1236361a(13) =11421757a(14) =147405903a(15) =1921739323a(16) =34678828327a(17) =635167573009

External references