Trajectory of 3 under map n->31n+1 if n odd, n->n/2 if n even.

Terms

a(0) =3a(1) =94a(2) =47a(3) =1458a(4) =729a(5) =22600a(6) =11300a(7) =5650a(8) =2825a(9) =87576a(10) =43788a(11) =21894a(12) =10947a(13) =339358a(14) =169679a(15) =5260050a(16) =2630025a(17) =81530776a(18) =40765388a(19) =20382694a(20) =10191347a(21) =315931758a(22) =157965879a(23) =4896942250a(24) =2448471125