Number of free polyominoes with n squares, having 180-degree rotational symmetry about the center of a square, and no other symmetry.

A351615

Number of free polyominoes with n squares, having 180-degree rotational symmetry about the center of a square, and no other symmetry.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =0a(6) =4a(7) =0a(8) =19a(9) =1a(10) =73a(11) =4a(12) =283a(13) =25a(14) =1090a(15) =106a(16) =4183a(17) =463a(18) =16105a(19) =1892a(20) =62170a(21) =7752a(22) =240907a(23) =31212a(24) =936447a(25) =125609a(26) =3651618a(27) =503165a(28) =14277519a(29) =2014826

External references