Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation.
A146019
Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =3a(7) =7a(8) =15a(9) =29a(10) =61a(11) =211a(12) =895a(13) =3955a(14) =16593a(15) =80999a(16) =462679a(17) =3239573a(18) =25414255a(19) =222500583a(20) =2101470837a(21) =23313975471a(22) =290908388247
External references
- oeis: A146019