a(n) = prime(n*(n+1)/2+2).

Terms

a(0) =3a(1) =5a(2) =11a(3) =19a(4) =37a(5) =59a(6) =83a(7) =113a(8) =163a(9) =211a(10) =269a(11) =337a(12) =409a(13) =487a(14) =587a(15) =673a(16) =787a(17) =907a(18) =1031a(19) =1163a(20) =1301a(21) =1471a(22) =1613a(23) =1789a(24) =1997a(25) =2179a(26) =2381a(27) =2617a(28) =2801a(29) =3049