verjun

摘要： 题意 求$$\prod_{i=1}^n\prod_{j=1}^n\frac{lcm(i,j)}{\gcd(i,j)}$$ $n\le10^6$ Sol 先把$lcm$化成$\gcd$ $$\prod_{i=1}^n\prod_{j=1}^n\frac{lcm(i,j)}{\gcd(i,j)}$$ $ 阅读全文