Floor((prime(n)/n)^n).

Terms

a(0) =2a(1) =2a(2) =4a(3) =9a(4) =51a(5) =103a(6) =498a(7) =1012a(8) =4649a(9) =42070a(10) =89055a(11) =738321a(12) =3054404a(13) =6649146a(14) =27548565a(15) =210132966a(16) =1537632445a(17) =3475617204a(18) =25067027254a(19) =101057153476a(20) =230767621110