Associated Mersenne numbers.

Terms

a(0) =0a(1) =1a(2) =3a(3) =1a(4) =3a(5) =11a(6) =9a(7) =8a(8) =27a(9) =37a(10) =33a(11) =67a(12) =117a(13) =131a(14) =192a(15) =341a(16) =459a(17) =613a(18) =999a(19) =1483a(20) =2013a(21) =3032a(22) =4623a(23) =6533a(24) =9477a(25) =14311a(26) =20829a(27) =30007a(28) =44544a(29) =65657