The a(n)-th composite number is 2^n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =20a(4) =45a(5) =96a(6) =201a(7) =414a(8) =851a(9) =1738a(10) =3531a(11) =7163a(12) =14483a(13) =29255a(14) =58993a(15) =118820a(16) =239143a(17) =480897a(18) =966550a(19) =1941540a(20) =3898356a(21) =7824444a(22) =15699344a(23) =31490742a(24) =63151054a(25) =126614174a(26) =253804612a(27) =508678161a(28) =1019341795a(29) =2042386082