Function problem

The function $f(n)$ satisfies $f(1)=1$ and $f(2n+1)=f(n)+2$ for $n \ge 0$.
Find $f(15)$.

$\begin{array}{|lrcll|} \hline n=1:& f(2*1+1) &=& f(1) + 2 \quad | \quad f(1)=1 \\ &f(3) &=& 1+2 \\ &f(3)&=& 3 \\ \hline n=3:& f(2*3+1) &=& f(3) + 2 \quad | \quad f(3)=3 \\ &f(7) &=& 3+2 \\ &f(7)&=& 5 \\ \hline n=7:& f(2*7+1) &=& f(7) + 2 \quad | \quad f(7)=5 \\ &f(15) &=& 5+2 \\ &\mathbf{ f(15) } &=& \mathbf{7} \\ \hline \end{array}$