Number of n X n binary arrays, symmetric about both diagonal and antidiagonal, with every 1 adjacent to at least one other 1, but at most one 1 adjacent horizontally and at most one 1 adjacent vertically.
A144056
Number of n X n binary arrays, symmetric about both diagonal and antidiagonal, with every 1 adjacent to at least one other 1, but at most one 1 adjacent horizontally and at most one 1 adjacent vertically.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =11a(4) =31a(5) =171a(6) =719a(7) =5907a(8) =40576a(9) =574191a(10) =6118805a(11) =134458817a(12) =2328856652a(13) =81657178991
External references
- oeis: A144056