Index of 5^n within sequence of numbers of form 2^i * 5^j.

Terms

a(0) =1a(1) =4a(2) =9a(3) =16a(4) =26a(5) =38a(6) =52a(7) =69a(8) =88a(9) =109a(10) =133a(11) =159a(12) =187a(13) =218a(14) =251a(15) =286a(16) =324a(17) =364a(18) =406a(19) =451a(20) =498a(21) =547a(22) =599a(23) =653a(24) =709a(25) =768a(26) =829a(27) =892a(28) =958a(29) =1026