English

On vanishing Fermat quotients and a bound of the Ihara sum

Number Theory 2011-04-21 v1

Abstract

We improve an estimate of A.Granville (1987) on the number of vanishing Fermat quotients qp()q_p(\ell) modulo a prime pp when \ell runs through primes N\ell \le N. We use this bound to obtain an unconditional improvement of the conditional (under the Generalised Riemann Hypothesis) estimate of Y. Ihara (2006) on a certain sum, related to vanishing Fermat quotients. In turn this sum appears in the study of the index of certain subfields of of cyclotomic fields \Q(exp(2πi/p2))\Q(\exp(2 \pi i/p^2)).

Keywords

Cite

@article{arxiv.1104.3910,
  title  = {On vanishing Fermat quotients and a bound of the Ihara sum},
  author = {Igor E. Shparlinski},
  journal= {arXiv preprint arXiv:1104.3910},
  year   = {2011}
}