Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1000-1000-1111-0001 pattern in any orientation.
A147272
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1000-1000-1111-0001 pattern in any orientation.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =1a(8) =1a(9) =5a(10) =13a(11) =25a(12) =49a(13) =141a(14) =407a(15) =1043a(16) =2925a(17) =11783a(18) =52869a(19) =254667a(20) =1211663
External references
- oeis: A147272