Primes that contain digits 1 and 2 only.

Terms

a(0) =2a(1) =11a(2) =211a(3) =2111a(4) =2221a(5) =12211a(6) =21121a(7) =21211a(8) =21221a(9) =22111a(10) =111121a(11) =111211a(12) =112111a(13) =112121a(14) =1111211a(15) =1121221a(16) =1212121a(17) =1212221a(18) =1221221a(19) =2121121a(20) =2211211a(21) =2221111a(22) =11221211a(23) =12111221a(24) =12121121a(25) =12121211a(26) =12122111a(27) =12122221a(28) =12212111a(29) =12222121