Exponential sums over primes formed with coefficients of primitive cusp forms

Let . f (n) be the coefficient of the logarithmic derivative for the Hecke L-function. In this paper we study the cancellation of the function . f (n) twisted with an additive character e(..n), . > 0, i.e. S f (x) = . x<n.2x . f (n)e(..n).