Number of chiral pairs of polyominoes with n cells that have precisely the symmetry group of order 4 generated by 90-degree rotations.

A144553

Number of chiral pairs of polyominoes with n cells that have precisely the symmetry group of order 4 generated by 90-degree rotations.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =1a(8) =0a(9) =0a(10) =0a(11) =3a(12) =2a(13) =0a(14) =0a(15) =12a(16) =7a(17) =0a(18) =0a(19) =44a(20) =25a(21) =0a(22) =0a(23) =165a(24) =90a(25) =0a(26) =0a(27) =603a(28) =319a(29) =0

External references