Primes having only {2, 4, 9} as digits.

Terms

a(0) =2a(1) =29a(2) =229a(3) =449a(4) =499a(5) =929a(6) =2999a(7) =4229a(8) =4999a(9) =9929a(10) =9949a(11) =22229a(12) =24229a(13) =24499a(14) =29429a(15) =42299a(16) =42499a(17) =42929a(18) =44249a(19) =44449a(20) =49429a(21) =49499a(22) =49999a(23) =94229a(24) =94949a(25) =94999a(26) =99929a(27) =222499a(28) =224299a(29) =224429