On the representation of the number of integral points of an elliptic   curve modulo a prime number
  In this paper we shall investigate the problem of the representation of the number of integral points of an elliptic curve modulo a prime number p. We present a way of expressing an exponential sum which involves polynomials of third degree, in explicit non-exponential terms. In the process, we present explicit formulas for the calculation of some series involving the Riemann Zeta function. 
Michael Th. Rassias
math.NT