Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either as two by three or three by two blocks.
A146156
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either as two by three or three by two blocks.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =4a(8) =7a(9) =11a(10) =20a(11) =47a(12) =126a(13) =349a(14) =1026a(15) =3169a(16) =10962a(17) =42335a(18) =178967a(19) =817710a(20) =4108982a(21) =22332287a(22) =134485764a(23) =875416554a(24) =6255533128a(25) =48551931040a(26) =415466055841
External references
- oeis: A146156