a(0) = 1; a(n) = a(n-1)+1 if n is even, otherwise a(n) = 2*a(n-1).

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =7a(5) =14a(6) =15a(7) =30a(8) =31a(9) =62a(10) =63a(11) =126a(12) =127a(13) =254a(14) =255a(15) =510a(16) =511a(17) =1022a(18) =1023a(19) =2046a(20) =2047a(21) =4094a(22) =4095a(23) =8190a(24) =8191a(25) =16382a(26) =16383a(27) =32766a(28) =32767a(29) =65534