Smallest start for a '3x+1' sequence containing 2^n.

Terms

a(0) =1a(1) =2a(2) =3a(3) =3a(4) =3a(5) =21a(6) =21a(7) =75a(8) =75a(9) =151a(10) =151a(11) =1365a(12) =1365a(13) =5461a(14) =5461a(15) =14563a(16) =14563a(17) =87381a(18) =87381a(19) =184111a(20) =184111a(21) =932067a(22) =932067a(23) =5592405a(24) =5592405a(25) =13256071a(26) =13256071a(27) =26512143a(28) =26512143a(29) =357913941