Primes having only {5, 7, 9} as digits.

Terms

a(0) =5a(1) =7a(2) =59a(3) =79a(4) =97a(5) =557a(6) =577a(7) =599a(8) =757a(9) =797a(10) =977a(11) =997a(12) =5557a(13) =5779a(14) =7559a(15) =7577a(16) =7757a(17) =7759a(18) =55579a(19) =55799a(20) =55997a(21) =57557a(22) =57559a(23) =57977a(24) =59557a(25) =59779a(26) =59797a(27) =59957a(28) =59999a(29) =75557