def sum_of_powers(ind):
    """Sum Of Powers function defined as:
    $$ f(x) = \sum_{i=1}^{n} \norm{x_i}^{(i+1)} $$
    with a search domain of $-1 < x_i < 1, 1 \leq i \leq n$.
    The global minimum is at $f(x_1, ..., x_n) = f(0, ..., 0) = 0.
    """
    return sum((abs(ind[i]) ** (i+1.) for i in range(len(ind)))),