Primes having only {2, 4, 5, 7} as digits.

Terms

a(0) =2a(1) =5a(2) =7a(3) =47a(4) =227a(5) =257a(6) =277a(7) =457a(8) =547a(9) =557a(10) =577a(11) =727a(12) =757a(13) =2447a(14) =2477a(15) =2557a(16) =2777a(17) =4447a(18) =4457a(19) =4547a(20) =5227a(21) =5477a(22) =5527a(23) =5557a(24) =7247a(25) =7457a(26) =7477a(27) =7547a(28) =7577a(29) =7727