Calculate the sum of ∑n=1∞1n2+2n\sum_{n=1}^{\infty} \frac{1}{n^2+2n}∑n=1∞n2+2n1.
12\frac{1}{2}21
34\frac{3}{4}43
14\frac{1}{4}41
23\frac{2}{3}32