Duplicate of A055010.

Terms

a(0) =0a(1) =2a(2) =5a(3) =11a(4) =23a(5) =47a(6) =95a(7) =191a(8) =383a(9) =767a(10) =1535a(11) =3071a(12) =6143a(13) =12287a(14) =24575a(15) =49151a(16) =98303