heureka knows how to sum up sequences such as this one in a formal manner. I don't!!. However, I can determine the "closed form" of ALL the denominators: (n^3+3n^2+2n). And then I can use sigma to sum them all up: ∑[4/(n^3+3n^2+2n), n, 1, 998]=0.99999799799799......etc. It clearly converges to 1 as n tends to infinity!!.