Index of 2^n within the sequence of the numbers of the form 2^i*10^j.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =10a(7) =13a(8) =16a(9) =19a(10) =23a(11) =27a(12) =31a(13) =35a(14) =40a(15) =45a(16) =50a(17) =56a(18) =62a(19) =68a(20) =75a(21) =82a(22) =89a(23) =96a(24) =104a(25) =112a(26) =120a(27) =129a(28) =138a(29) =147