Hello,

I am reading some material on circle method. Right now I am at its application to the binary Goldbach problem. To obtain a certain bound the fact $\sum_{n> X} 1/ \phi(n)^2 = O(1/X)$ is used. Could anyone please help me how to solve it?

Here $\phi$ is the Euler totient function. And I would like the result without $\epsilon$.

Thank you.