Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in two by two blocks.
A145861
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in two by two blocks.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =4a(4) =4a(5) =13a(6) =13a(7) =58a(8) =68a(9) =386a(10) =540a(11) =3520a(12) =6019a(13) =47375a(14) =94643a(15) =905453a(16) =2187052a(17) =24871767a(18) =71992142a(19) =980875049a(20) =3393779522a(21) =55564082030a(22) =230467066626
External references
- oeis: A145861