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

A075219

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

Terms

    a(0) =1a(1) =0a(2) =1a(3) =1a(4) =4a(5) =4a(6) =21a(7) =32a(8) =111a(9) =200a(10) =462a(11) =1162a(12) =1875a(13) =4195a(14) =9410a(15) =17978a(16) =24034a(17) =73175a(18) =79925a(19) =251808a(20) =358096a(21) =631919a(22) =796571a(23) =3104082a(24) =2980476a(25) =6088310a(26) =10167660a(27) =23661369a(28) =21477012a(29) =84485584

External references