Trajectory of 3 under map n->39n+1 if n odd, n->n/2 if n even.

Terms

a(0) =3a(1) =118a(2) =59a(3) =2302a(4) =1151a(5) =44890a(6) =22445a(7) =875356a(8) =437678a(9) =218839a(10) =8534722a(11) =4267361a(12) =166427080a(13) =83213540a(14) =41606770a(15) =20803385a(16) =811332016a(17) =405666008a(18) =202833004a(19) =101416502a(20) =50708251a(21) =1977621790a(22) =988810895