Trajectory of 3 under map n->7n-1 if n odd, n->n/2 if n even.

Terms

a(0) =3a(1) =20a(2) =10a(3) =5a(4) =34a(5) =17a(6) =118a(7) =59a(8) =412a(9) =206a(10) =103a(11) =720a(12) =360a(13) =180a(14) =90a(15) =45a(16) =314a(17) =157a(18) =1098a(19) =549a(20) =3842a(21) =1921a(22) =13446a(23) =6723a(24) =47060a(25) =23530a(26) =11765a(27) =82354a(28) =41177a(29) =288238