Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.
A145956
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =3a(6) =7a(7) =13a(8) =37a(9) =103a(10) =343a(11) =1549a(12) =7241a(13) =37919a(14) =236383a(15) =1636125a(16) =13465687a(17) =128312593a(18) =1395150187a(19) =17424865195a(20) =251739719221
External references
- oeis: A145956