Primes that contain digits 3 and 7 only.

Terms

a(0) =3a(1) =7a(2) =37a(3) =73a(4) =337a(5) =373a(6) =733a(7) =773a(8) =3373a(9) =3733a(10) =7333a(11) =33377a(12) =33773a(13) =37337a(14) =77377a(15) =77773a(16) =333337a(17) =333737a(18) =373777a(19) =377737a(20) =733333a(21) =733373a(22) =737773a(23) =773777a(24) =777373a(25) =777737a(26) =3333373a(27) =3333773a(28) =3337333a(29) =3337777