[∞ ∑ n=1] 1 / [(2n+1)] > [∞ ∑ n=1] 1 / [(2n+2)]= (1/2)[∞ ∑ n=1] 1 / [(n+)] = (1/2)[∞ ∑ n=2] (1 / n)后者为调和级数（是p=1时得p级数），发散，故原级数发散。
