Free polyominoes with 4n squares, having 90-degree rotational symmetry about a square corner.
A234009
Free polyominoes with 4n squares, having 90-degree rotational symmetry about a square corner.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =10a(4) =35a(5) =114a(6) =403a(7) =1432a(8) =5239a(9) =19271a(10) =71820a(11) =269417a(12) =1017920a(13) =3864879
External references
- oeis: A234009