Build log-stepped array from `start` to `stop` in `n` steps.

def even_mults(start:float, stop:float, n:int)->np.ndarray:
    "Build log-stepped array from `start` to `stop` in `n` steps."
    mult = stop/start
    step = mult**(1/(n-1))
    return np.array([start*(step**i) for i in range(n)])