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

Terms

a(0) =4a(1) =6a(2) =9a(3) =46a(4) =49a(5) =69a(6) =94a(7) =446a(8) =466a(9) =469a(10) =649a(11) =669a(12) =694a(13) =699a(14) =949a(15) =4449a(16) =4469a(17) =4499a(18) =4666a(19) =4694a(20) =4699a(21) =4946a(22) =6499a(23) =6646a(24) =6649a(25) =6694a(26) =6999a(27) =9446a(28) =9449a(29) =9466