a(n) = floor(a(n-1)/3) if this is positive and not yet in the sequence, otherwise a(n) = 7*a(n-1).

Terms

a(0) =1a(1) =7a(2) =2a(3) =14a(4) =4a(5) =28a(6) =9a(7) =3a(8) =21a(9) =147a(10) =49a(11) =16a(12) =5a(13) =35a(14) =11a(15) =77a(16) =25a(17) =8a(18) =56a(19) =18a(20) =6a(21) =42a(22) =294a(23) =98a(24) =32a(25) =10a(26) =70a(27) =23a(28) =161a(29) =53