Numbers with semiprime digits (digits 4, 6, 9 only).

Terms

a(0) =4a(1) =6a(2) =9a(3) =44a(4) =46a(5) =49a(6) =64a(7) =66a(8) =69a(9) =94a(10) =96a(11) =99a(12) =444a(13) =446a(14) =449a(15) =464a(16) =466a(17) =469a(18) =494a(19) =496a(20) =499a(21) =644a(22) =646a(23) =649a(24) =664a(25) =666a(26) =669a(27) =694a(28) =696a(29) =699