Composite numbers whose prime factors have no digits other than 4's and 9's.

Terms

a(0) =201601a(1) =224051a(2) =249001a(3) =2244551a(4) =2494501a(5) =4467101a(6) =4964551a(7) =19957601a(8) =22180051a(9) =22225051a(10) =22449551a(11) =24700001a(12) =24949501a(13) =24990001a(14) =42632101a(15) =42654551a(16) =47379551a(17) =47404501a(18) =49735051a(19) =90518849a(20) =98982601a(21) =100598899a(22) =111801449a(23) =124251499a(24) =199557601a(25) =221780051a(26) =222200551a(27) =247445501