变量MATH$sum_{i=0}^n i^2 = frac{(n^2+n)(2n+1)}{6}$$sum_{i=0}^n i^2 = frac{(n^2+n)(2n+1)}{6}$$$sum_{i=0}^n i^2 = frac{(n^2+n)(2n+1)}{6}$$`$$sum_{i=0}^n i^2 = frac{(n^2+n)(2n+1)}{6}$$ 赞微海报分享
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