x -> x/2 if x even, x -> 3x - 1 if x odd.

Terms

a(0) =87a(1) =260a(2) =130a(3) =65a(4) =194a(5) =97a(6) =290a(7) =145a(8) =434a(9) =217a(10) =650a(11) =325a(12) =974a(13) =487a(14) =1460a(15) =730a(16) =365a(17) =1094a(18) =547a(19) =1640a(20) =820a(21) =410a(22) =205a(23) =614a(24) =307a(25) =920a(26) =460a(27) =230a(28) =115a(29) =344