Half the number of n X n binary matrices, symmetric under 90-degree rotation, having equal row sums.
A140884
Half the number of n X n binary matrices, symmetric under 90-degree rotation, having equal row sums.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =4a(4) =3a(5) =13a(6) =43a(7) =580a(8) =1897a(9) =23851a(10) =149041a(11) =14348161a(12) =74552521a(13) =7849966951a(14) =311500453881
External references
- oeis: A140884