Primes that contain digits 1 and 3 only.

Terms

a(0) =3a(1) =11a(2) =13a(3) =31a(4) =113a(5) =131a(6) =311a(7) =313a(8) =331a(9) =3313a(10) =3331a(11) =11113a(12) =11131a(13) =11311a(14) =13313a(15) =13331a(16) =31333a(17) =33113a(18) =33311a(19) =33331a(20) =113111a(21) =113131a(22) =131111a(23) =131113a(24) =131311a(25) =311111a(26) =313133a(27) =313331a(28) =313333a(29) =331333