The 3x-1 map: a(n) = n/2 if n is even, 3n-1 if n is odd.

Terms

a(0) =63a(1) =188a(2) =94a(3) =47a(4) =140a(5) =70a(6) =35a(7) =104a(8) =52a(9) =26a(10) =13a(11) =38a(12) =19a(13) =56a(14) =28a(15) =14a(16) =7a(17) =20a(18) =10a(19) =5a(20) =14a(21) =7a(22) =20a(23) =10a(24) =5a(25) =14a(26) =7a(27) =20a(28) =10a(29) =5