Primes that contain digits 2 and 7 only.

Terms

a(0) =2a(1) =7a(2) =227a(3) =277a(4) =727a(5) =2777a(6) =7727a(7) =22277a(8) =22727a(9) =22777a(10) =27277a(11) =72227a(12) =72277a(13) =72727a(14) =272227a(15) =272777a(16) =727777a(17) =777277a(18) =2227727a(19) =2227777a(20) =2272727a(21) =2277727a(22) =2727727a(23) =2772227a(24) =7272227a(25) =7722277a(26) =7727777a(27) =7772777a(28) =7777727a(29) =22227277