Number of polyhexes with n cells that tile the plane by 180-degree rotation (Conway criterion) but not by translation.

A075210

Number of polyhexes with n cells that tile the plane by 180-degree rotation (Conway criterion) but not by translation.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =9a(5) =39a(6) =197a(7) =721a(8) =2717a(9) =8211a(10) =19836a(11) =74497a(12) =132611a(13) =403534a(14) =1127416a(15) =2364402a(16) =4173316a(17) =15604400a(18) =21318428a(19) =73965916a(20) =154211880

External references