Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation.
A146148
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =5a(5) =7a(6) =25a(7) =61a(8) =137a(9) =491a(10) =1895a(11) =6799a(12) =35271a(13) =188161a(14) =1045823a(15) =6942831a(16) =54475785a(17) =429190219a(18) =4220050567a(19) =45840848045a(20) =555820995851
External references
- oeis: A146148