Number of n X n binary matrices, symmetric about both diagonal and antidiagonal, with no more than 1 one in any 2 X 2 subblock.
A141485
Number of n X n binary matrices, symmetric about both diagonal and antidiagonal, with no more than 1 one in any 2 X 2 subblock.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =5a(4) =4a(5) =21a(6) =21a(7) =158a(8) =225a(9) =2181a(10) =4032a(11) =53517a(12) =135895a(13) =2389270a(14) =8052775a(15) =191382781a(16) =871834816a(17) =27710789575a(18) =168906089337
External references
- oeis: A141485