Published online by Cambridge University Press: 26 February 2010
Let q be a prime number and let a = (a1, …, as) be an s-tuple of distinct integers modulo q. For any x coprime with q, let be such that
. For fixed s and q→∞ an asymptotic formula is given for the number of residue classes x modulo q for which
The more general case, when q is not necessarily prime and x is restricted to lie in a given subinterval of [1, q], is also treated.