f(n)=\left\{\begin{array}{ll}
f\left(\frac{n-1}2\right)+f\left(\frac{n-3}2\right),&\quad n\equiv 1\pmod 2\\
f\left(\frac n 2\right)+f\left(\frac{n-2}2\right),&\quad\hbox{ina\v ce}\end{array}\right.