Index of 2^n within the sequence of the numbers of the form 2^i * 9^j.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =10a(7) =13a(8) =16a(9) =19a(10) =23a(11) =27a(12) =31a(13) =36a(14) =41a(15) =46a(16) =52a(17) =58a(18) =64a(19) =70a(20) =77a(21) =84a(22) =91a(23) =99a(24) =107a(25) =115a(26) =124a(27) =133a(28) =142a(29) =152