Index of 5^n within the sequence of the numbers of the form 5^i*6^j.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =11a(5) =16a(6) =22a(7) =29a(8) =37a(9) =46a(10) =55a(11) =65a(12) =76a(13) =88a(14) =101a(15) =115a(16) =130a(17) =146a(18) =163a(19) =181a(20) =199a(21) =218a(22) =238a(23) =259a(24) =281a(25) =304a(26) =328a(27) =353a(28) =379a(29) =406