Index of 8^n within the sequence of the numbers of the form 5^i*8^j.

Terms

a(0) =1a(1) =3a(2) =6a(3) =10a(4) =16a(5) =23a(6) =31a(7) =41a(8) =52a(9) =64a(10) =77a(11) =92a(12) =108a(13) =125a(14) =144a(15) =164a(16) =185a(17) =207a(18) =231a(19) =256a(20) =282a(21) =310a(22) =339a(23) =369a(24) =401a(25) =434a(26) =468a(27) =503a(28) =540a(29) =578