Totient summatory function

In number theory, the totient summatory function is a summatory function of Euler's totient function defined by: It is the number of coprime integer pairs {p, q}, 1 ≤ p ≤ q ≤ n. Using Möbius inversion to the totient function, we obtain Φ(n) has the asymptotic expansion where ζ(2) is the Riemann zeta function for the value 2. Φ(n) is the number of coprime integer pairs {p, q}, 1 ≤ p ≤ q ≤ n. The summatory of reciprocal totient function is defined as Edmund Landau showed in 1900 that this function has the asymptotic behavior where γ is the Euler–Mascheroni constant, and The constant A = 1.943596... is sometimes known as Landau's totient constant.