'3x+1' record-setters (blowup factor).

Terms

a(0) =1a(1) =3a(2) =7a(3) =15a(4) =27a(5) =703a(6) =1819a(7) =4255a(8) =4591a(9) =9663a(10) =26623a(11) =60975a(12) =77671a(13) =113383a(14) =159487a(15) =1212415a(16) =2684647a(17) =3041127a(18) =3873535a(19) =4637979a(20) =5656191a(21) =6416623a(22) =6631675a(23) =19638399a(24) =80049391a(25) =210964383a(26) =319804831a(27) =1410123943a(28) =70141259775a(29) =77566362559