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

Terms

a(0) =1a(1) =5a(2) =12a(3) =22a(4) =36a(5) =53a(6) =73a(7) =97a(8) =124a(9) =154a(10) =188a(11) =225a(12) =265a(13) =309a(14) =356a(15) =406a(16) =460a(17) =517a(18) =577a(19) =641a(20) =708a(21) =778a(22) =852a(23) =929a(24) =1009a(25) =1093a(26) =1180a(27) =1270a(28) =1364a(29) =1461