记 n2n^2n2 的正约数为 d1,d2,......,dmd_1,d_2,......,d_md1,d2,......,dm ,求证:
∑i=1m1n+d=m2n\sum_{i=1}^{m}\frac{1}{n+d}= \frac{m}{2n}∑i=1mn+d1=2nm
拜谢