Primes having only {4, 7, 8} as digits.

Terms

a(0) =7a(1) =47a(2) =487a(3) =787a(4) =877a(5) =887a(6) =4447a(7) =4787a(8) =4877a(9) =7477a(10) =7487a(11) =7877a(12) =8447a(13) =8747a(14) =8887a(15) =44777a(16) =44887a(17) =47777a(18) =48487a(19) =48787a(20) =48847a(21) =74747a(22) =74887a(23) =77447a(24) =77477a(25) =77747a(26) =78487a(27) =78787a(28) =78877a(29) =78887