Number of n X n binary matrices, symmetric about both diagonal and antidiagonal, with no more than 2 ones in any 2 X 2 subblock.

A141505

Number of n X n binary matrices, symmetric about both diagonal and antidiagonal, with no more than 2 ones in any 2 X 2 subblock.

Terms

    a(0) =1a(1) =2a(2) =3a(3) =9a(4) =21a(5) =113a(6) =469a(7) =4085a(8) =28379a(9) =421721a(10) =4946881a(11) =123415785a(12) =2438547133a(13) =102642272877

External references