Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a 2 X 2 elbow 1,1 1,2 2,1 in any orientation.
A145940
Number of n X n binary arrays symmetric about the diagonal and 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) =3a(5) =3a(6) =7a(7) =7a(8) =23a(9) =23a(10) =131a(11) =131a(12) =971a(13) =971a(14) =9431a(15) =9431a(16) =139347a(17) =139347a(18) =2886057a(19) =2886057a(20) =82544813a(21) =82544813a(22) =3341873733a(23) =3341873733a(24) =191910369845a(25) =191910369845
External references
- oeis: A145940