请问 ∑i=1n∑j=1n[gcd(i,j)=1]\sum_{i=1}^n\sum_{j=1}^n[gcd(i,j)=1]∑i=1n∑j=1n[gcd(i,j)=1] 是否等于 2∑i=1nφ(i)2\sum_{i=1}^n\varphi(i)2∑i=1nφ(i)
