On Page 11 of Second edition of Concrete Mathematics, it reads as
The induction step has two parts, depending on whether $l$ is even or odd. If $m > 0$ and $2^m + l= 2n$, then $l$ is even and
$J(2^m +l) = 2J(2^{m-1} +l/2)-1 = 2(2l/2+1)-1 = 2l+1$
by (1.8)
Here I didn't get how $2J(2^{m-1} +l/2)-1 $ is reduced to $2(2l/2+1)-1$
Please Help.