a(n) = (n+1)*2^(n-1) - 1.

Terms

a(0) =1a(1) =5a(2) =15a(3) =39a(4) =95a(5) =223a(6) =511a(7) =1151a(8) =2559a(9) =5631a(10) =12287a(11) =26623a(12) =57343a(13) =122879a(14) =262143a(15) =557055a(16) =1179647a(17) =2490367a(18) =5242879a(19) =11010047a(20) =23068671a(21) =48234495a(22) =100663295a(23) =209715199a(24) =436207615a(25) =905969663a(26) =1879048191a(27) =3892314111a(28) =8053063679