Fibonacci concatenation

Let's define Fibonacci concatenation sequence as follows: - $f[0] = 0$, $f[1] = 1$ - $f[i] = f[i-1] + f[i-2]$, for every $i \geq 2$ Here $f[i]$ denotes the $i^{th}$ Fibonacci concatenation number and $+$ represents concatenation. For example, $f[2] = f[1] + f[0] = 1 + 0 = 10$, $f[3] = f[2] + f[1] =$ $10 + 1 = $ $101$. Given an integer $n$, you have to determine the sum of digits of all subseq