Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 3X3 el 1,1 1,2 1,3 2,3 3,3 in any orientation.

A146034

Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 3X3 el 1,1 1,2 1,3 2,3 3,3 in any orientation.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =3a(5) =7a(6) =15a(7) =43a(8) =83a(9) =271a(10) =633a(11) =3283a(12) =9541a(13) =54293a(14) =204827a(15) =1408893a(16) =6437305a(17) =54681853a(18) =303651861a(19) =3282191633a(20) =22628378377a(21) =297350762879

External references