2^(n-1) - floor((2^(n-1) - 1)/(n-1)).

Terms

a(0) =1a(1) =3a(2) =6a(3) =13a(4) =26a(5) =54a(6) =110a(7) =225a(8) =456a(9) =922a(10) =1862a(11) =3755a(12) =7562a(13) =15214a(14) =30584a(15) =61441a(16) =123362a(17) =247581a(18) =496694a(19) =996148a(20) =1997288a(21) =4003654a(22) =8023886a(23) =16078166a(24) =32212255a(25) =64527754a(26) =129246702a(27) =258848476a(28) =518358122a(29) =1037950430