Primes having only {1, 5, 7} as digits.

Terms

a(0) =5a(1) =7a(2) =11a(3) =17a(4) =71a(5) =151a(6) =157a(7) =557a(8) =571a(9) =577a(10) =751a(11) =757a(12) =1117a(13) =1151a(14) =1171a(15) =1511a(16) =1571a(17) =1777a(18) =5171a(19) =5557a(20) =5711a(21) =5717a(22) =7151a(23) =7177a(24) =7517a(25) =7577a(26) =7717a(27) =7757a(28) =11117a(29) =11171