Primes having only {7, 8, 9} as digits.

Terms

a(0) =7a(1) =79a(2) =89a(3) =97a(4) =787a(5) =797a(6) =877a(7) =887a(8) =977a(9) =997a(10) =7789a(11) =7877a(12) =7879a(13) =8779a(14) =8887a(15) =8999a(16) =9787a(17) =9887a(18) =77797a(19) =77899a(20) =77977a(21) =77999a(22) =78779a(23) =78787a(24) =78797a(25) =78877a(26) =78887a(27) =78889a(28) =78977a(29) =78979