Index of 3^n within sequence of numbers of form 2^i*3^j (A003586).

Terms

a(0) =1a(1) =3a(2) =7a(3) =12a(4) =19a(5) =27a(6) =37a(7) =49a(8) =62a(9) =77a(10) =93a(11) =111a(12) =131a(13) =152a(14) =175a(15) =199a(16) =225a(17) =252a(18) =281a(19) =312a(20) =344a(21) =378a(22) =413a(23) =450a(24) =489a(25) =529a(26) =571a(27) =614a(28) =659a(29) =705