Let $q\ge 3$ be a positive integer. For any integers $m$ and $n$, the two-term exponential sum $C(m,n,k;q)$ is defined by $C(m,n,k;q)={\sum }_{a=1}^{q}e((m{a}^k+na)/q)$, where $e\left(y\right)={\mathrm{e}}^{2\pi \mathrm{i}y}$. In this paper, we use the properties of Gauss sums and the estimate for Dirichlet character of polynomials to study the mean value problem involving two-term exponential sums and Dirichlet character of polynomials, and give an interesting asymptotic formula for it.

The main purpose of this paper is to use the M. Toyoizumi's important work, the properties of the Dedekind sums and the estimates for character sums to study a hybrid mean value of the Dedekind sums, and give a sharper asymptotic formula for it.

Let Γ ⊂ ℚ * be a finitely generated subgroup and let p be a prime such that the reduction group Γₚ is a well defined subgroup of the multiplicative group ₚ*. We prove an asymptotic formula for the average of the number of primes p ≤ x for which [ₚ*:Γₚ] = m. The average is taken over all finitely generated subgroups $\Gamma =⟨a₁,...,a_r⟩\subset \mathbb{Q}*$, with $a_i\in \mathbb{Z}$ and $a_i\le T_i$, with a range of uniformity $T_i>exp\left(4{\left(logxloglogx\right)}^{1/2}\right)$ for every i = 1,...,r. We also prove an asymptotic formula for the mean square of the error terms in the asymptotic formula with a similar...

In this paper, we apply character sum estimates to study products of factorials modulo $p$.

Let $A$ be a finite subset of an abelian group $G$ and let $P$ be a closed half-plane of the complex plane, containing zero. We show that (unless $A$ possesses a special, explicitly indicated structure) there exists a non-trivial Fourier coefficient of the indicator function of $A$ which belongs to $P$. In other words, there exists a non-trivial character $\chi \in \widehat{G}$ such that ${\sum }_{a\in A}\chi \left(a\right)\in P$.

We show that for any given integer $k$ there exist infinitely many consecutive square-free numbers of the type $x^2+y^2+z^2+k$, $x^2+y^2+z^2+k+1$. We also establish an asymptotic formula for $1\le x,y,z\le H$ such that $x^2+y^2+z^2+k$, $x^2+y^2+z^2+k+1$ are square-free. The method we used in this paper is due to Tolev.