Number of fixed polyiamonds of area n with holes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =6a(9) =48a(10) =270a(11) =1268a(12) =5292a(13) =20439a(14) =74814a(15) =263355a(16) =901008a(17) =3017115a(18) =9937114a(19) =32304714a(20) =103923708a(21) =331464966a(22) =1049720568a(23) =3304628530a(24) =10351016262a(25) =32283173154a(26) =100314652764a(27) =310715722757a(28) =959736443148