a(n) is such that the a(n)-th composite number is (n-th prime)^2.

Terms

a(0) =1a(1) =4a(2) =15a(3) =33a(4) =90a(5) =129a(6) =227a(7) =288a(8) =429a(9) =694a(10) =798a(11) =1149a(12) =1417a(13) =1565a(14) =1879a(15) =2399a(16) =2993a(17) =3201a(18) =3879a(19) =4365a(20) =4623a(21) =5429a(22) =6002a(23) =6920a(24) =8245a(25) =8948a(26) =9314a(27) =10067a(28) =10457a(29) =11245