Primes having only {2, 5, 6, 7} as digits.

Terms

a(0) =2a(1) =5a(2) =7a(3) =67a(4) =227a(5) =257a(6) =277a(7) =557a(8) =577a(9) =677a(10) =727a(11) =757a(12) =2267a(13) =2557a(14) =2657a(15) =2677a(16) =2767a(17) =2777a(18) =5227a(19) =5527a(20) =5557a(21) =5657a(22) =6257a(23) =6277a(24) =6577a(25) =7577a(26) =7727a(27) =7757a(28) =22277a(29) =22567