Index of 6^n within the sequence of the numbers of the form 6^i*7^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) =91a(14) =104a(15) =118a(16) =133a(17) =149a(18) =166a(19) =184a(20) =203a(21) =223a(22) =244a(23) =266a(24) =289a(25) =313a(26) =337a(27) =362a(28) =388a(29) =415