Number of fixed polyiamonds of area n without holes.

Terms

a(0) =2a(1) =3a(2) =6a(3) =14a(4) =36a(5) =94a(6) =250a(7) =675a(8) =1832a(9) =5005a(10) =13746a(11) =37901a(12) =104902a(13) =291312a(14) =811346a(15) =2265905a(16) =6343854a(17) =17801383a(18) =50057400a(19) =141034248a(20) =398070362a(21) =1125426581a(22) =3186725646a(23) =9036406687a(24) =25658313188a(25) =72946289247a(26) =207628101578a(27) =591622990214