Primes having only {2, 4, 7, 8} as digits.

Terms

a(0) =2a(1) =7a(2) =47a(3) =227a(4) =277a(5) =487a(6) =727a(7) =787a(8) =827a(9) =877a(10) =887a(11) =2287a(12) =2447a(13) =2477a(14) =2777a(15) =2887a(16) =4447a(17) =4787a(18) =4877a(19) =7247a(20) =7477a(21) =7487a(22) =7727a(23) =7877a(24) =8287a(25) =8447a(26) =8747a(27) =8887a(28) =22247a(29) =22277