Iterates A212439, starting from 0.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =13a(5) =27a(6) =54a(7) =108a(8) =216a(9) =433a(10) =867a(11) =1734a(12) =3469a(13) =6939a(14) =13878a(15) =27756a(16) =55512a(17) =111025a(18) =222050a(19) =444101a(20) =888202a(21) =1776404a(22) =3552808a(23) =7105617a(24) =14211235a(25) =28422470a(26) =56844941a(27) =113689883a(28) =227379766a(29) =454759532