Lucky numbers with only prime digits.

Terms

a(0) =3a(1) =7a(2) =25a(3) =33a(4) =37a(5) =73a(6) =75a(7) =223a(8) =235a(9) =237a(10) =273a(11) =327a(12) =357a(13) =535a(14) =537a(15) =553a(16) =577a(17) =723a(18) =727a(19) =735a(20) =777a(21) =2253a(22) =2257a(23) =2277a(24) =2323a(25) =2335a(26) =2355a(27) =2523a(28) =2527a(29) =2557