Primes with exactly three 3's.

Terms

a(0) =2333a(1) =3313a(2) =3323a(3) =3331a(4) =3343a(5) =3373a(6) =3433a(7) =3533a(8) =3733a(9) =3833a(10) =5333a(11) =7333a(12) =10333a(13) =13033a(14) =13313a(15) =13331a(16) =13337a(17) =13339a(18) =13633a(19) =13933a(20) =16333a(21) =17333a(22) =19333a(23) =20333a(24) =23339a(25) =23633a(26) =23833a(27) =29333a(28) =30133a(29) =30313