Primes consisting only of digits 4 and 9 occurring with equal frequency.

Terms

a(0) =44994949a(1) =49444999a(2) =49494499a(3) =49499449a(4) =94449499a(5) =4449449999a(6) =4449494999a(7) =4494494999a(8) =4494499949a(9) =4494949499a(10) =4494994499a(11) =4499449949a(12) =4499494949a(13) =4499944949a(14) =4944499949a(15) =4949444999a(16) =4994449949a(17) =9444499949a(18) =9444994499a(19) =9449494499a(20) =9449494949a(21) =9499444499a(22) =9944944949