4-almost primes with semiprime digits (digits 4, 6, 9 only).

Terms

a(0) =444a(1) =644a(2) =664a(3) =666a(4) =966a(5) =996a(6) =999a(7) =4444a(8) =4466a(9) =4494a(10) =4696a(11) =4964a(12) =6644a(13) =6666a(14) =6699a(15) =9444a(16) =9496a(17) =9646a(18) =9964a(19) =9966a(20) =9999a(21) =44444a(22) =44499a(23) =44646a(24) =44996a(25) =46444a(26) =46449a(27) =46964a(28) =46996a(29) =49444