Primes that contain digits 1 and 7 only.

Terms

a(0) =7a(1) =11a(2) =17a(3) =71a(4) =1117a(5) =1171a(6) =1777a(7) =7177a(8) =7717a(9) =11117a(10) =11171a(11) =11177a(12) =11717a(13) =11777a(14) =17117a(15) =71171a(16) =71711a(17) =71777a(18) =77171a(19) =77711a(20) =1111711a(21) =1111771a(22) =1117111a(23) =1117117a(24) =1117177a(25) =1171111a(26) =1171117a(27) =1171771a(28) =1177171a(29) =1177711