∑i=1a−1[amod ⌊a−1i⌋+amod (⌊ai+1⌋+1)]×(⌊a−1i⌋−⌊ai+1⌋)\sum_{i=1}^{a-1} \left[a\mod\left\lfloor \dfrac{a-1}{i}\right\rfloor+a\mod\left(\left\lfloor \dfrac{a}{i+1}\right\rfloor+1\right)\right]\times\left(\left\lfloor \dfrac{a-1}{i}\right\rfloor-\left\lfloor \dfrac{a}{i+1}\right\rfloor\right)∑i=1a−1[amod⌊ia−1⌋+amod(⌊i+1a⌋+1)]×(⌊ia−1⌋−⌊i+1a⌋)
为什么显示不出来？
