2: The problem arises around 3k, which is a place that moves, which is in general difficult to avoid. However, here these troublesome points go away to infinity, so if we consider some region away from infinity, then sooner or later these troublesome points leave it. In other words, it is enough to cut away some neighborhood of infinity. Indeed, choose arbitrary a > 0. Since k goes to infinity, we may assume that k > a. Then

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