Half the number of n X n binary matrices, symmetric under horizontal and vertical reflection, having equal row sums.
A140453
Half the number of n X n binary matrices, symmetric under horizontal and vertical reflection, having equal row sums.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =3a(4) =10a(5) =28a(6) =164a(7) =905a(8) =9826a(9) =103126a(10) =2031252a(11) =43437282a(12) =1622278624a(13) =66141208960
External references
- oeis: A140453