Smallest sequence which lists the position of digits "4" in the sequence.

Terms

a(0) =2a(1) =4a(2) =5a(3) =44a(4) =50a(5) =51a(6) =52a(7) =53a(8) =55a(9) =56a(10) =57a(11) =58a(12) =59a(13) =60a(14) =61a(15) =62a(16) =63a(17) =65a(18) =66a(19) =67a(20) =68a(21) =69a(22) =70a(23) =400a(24) =500a(25) =4444a(26) =5444a(27) =44444a(28) =45444a(29) =444000