A007318 * A143098.

Terms

a(0) =1a(1) =3a(2) =4a(3) =6a(4) =13a(5) =30a(6) =64a(7) =129a(8) =256a(9) =510a(10) =1021a(11) =2046a(12) =4096a(13) =8193a(14) =16384a(15) =32766a(16) =65533a(17) =131070a(18) =262144a(19) =524289a(20) =1048576a(21) =2097150a(22) =4194301a(23) =8388606a(24) =16777216a(25) =33554433a(26) =67108864a(27) =134217726a(28) =268435453a(29) =536870910