Number of polyiamonds with n cells that tile the plane.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =4a(5) =12a(6) =23a(7) =66a(8) =139a(9) =341a(10) =567a(11) =2034a(12) =2495a(13) =6354a(14) =12908a(15) =30261a(16) =26556a(17) =110145a(18) =95967a(19) =377523a(20) =499672a(21) =788726a(22) =845130a(23) =4998370a(24) =3694670a(25) =7406217a(26) =13175181a(27) =33557076a(28) =22381719a(29) =117770863