Index of 9^n within the sequence of the numbers of the form 9^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) =67a(12) =79a(13) =92a(14) =106a(15) =121a(16) =137a(17) =154a(18) =172a(19) =191a(20) =211a(21) =232a(22) =253a(23) =275a(24) =298a(25) =322a(26) =347a(27) =373a(28) =400a(29) =428