Published online by Cambridge University Press: 20 November 2020
We consider the sum $\sum 1/\gamma $, where
$\gamma $ ranges over the ordinates of nontrivial zeros of the Riemann zeta-function in an interval
$(0,T]$, and examine its behaviour as
$T \to \infty $. We show that, after subtracting a smooth approximation
$({1}/{4\pi }) \log ^2(T/2\pi ),$ the sum tends to a limit
$H \approx -0.0171594$, which can be expressed as an integral. We calculate H to high accuracy, using a method which has error
$O((\log T)/T^2)$. Our results improve on earlier results by Hassani [‘Explicit approximation of the sums over the imaginary part of the non-trivial zeros of the Riemann zeta function’, Appl. Math. E-Notes 16 (2016), 109–116] and other authors.
The third author is supported by ARC Grants DP160100932 and FT160100094; the second author is supported by ARC Grant DP160100932 and EPSRC Grant EP/K034383/1.