Index of 8^n within the sequence of the numbers of the form 8^i*10^j.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =11a(5) =16a(6) =22a(7) =29a(8) =37a(9) =46a(10) =56a(11) =66a(12) =77a(13) =89a(14) =102a(15) =116a(16) =131a(17) =147a(18) =164a(19) =182a(20) =201a(21) =220a(22) =240a(23) =261a(24) =283a(25) =306a(26) =330a(27) =355a(28) =381a(29) =408