Generalized problem of divisors with natural numbers whose binary expansions have special type
K. M. Eminyanab a Bauman Moscow State Technical University
b Financial University under the Government of the Russian Federation, Moscow
Abstract:
Let
$\tau_k(n)$ be the number of solutions of the equation
$x_{1}x_{2}\cdots x_{k}=n$ in natural numbers
$x_{1}$,
$x_{2}$,
$\ldots,$ $ x_{k}$. Let
$$
D_k(x)=\sum_{n\leqslant x}\tau_k(n).
$$
The problem of obtaining of asymptotic formula for
$D_k(x)$ is called Dirichlet divisors problem when
$k=2$, and generalyzed Dirichlet divisors problem when
$k\geqslant 3$.
This asymptotic formula has the form
$$
D_k (x)=x P_{k-1}(\log x)+O(x^{\alpha_k +\varepsilon}),
$$
where
$ P_{k-1}(x)$ — is the polynomial of the degree
$k-1$,
$0<\alpha_k<1$,
$\varepsilon >0$ — is arbitrary small number.
Generalyzed Dirichlet divisor problem has a rich history.
In 1849, L. Dirichlet [1] proved , that
$$
\alpha_k \leqslant 1-\frac{1}{k}, \quad k\geqslant 2.
$$
In 1903, G. Voronoi [2]
$$
\alpha_k \leqslant 1-\frac{1}{k+1}, \quad k\geqslant 2.
$$
(see also [3])
In 1922, G. Hardy and J. Littlewood [4] proved that
$$
\alpha_k \leqslant 1-\frac{3}{k+2}, \quad k\geqslant 4.
$$
In 1979, D. R. Heath-Brown [5] proved that
$$
\alpha_k \leqslant 1-\frac{3}{k}, \quad k\geqslant 8.
$$
In 1972, A. A. Karatsuba got a remarkable result [6].
His uniform estimate of the remainder term has the form
$$
O(x^{1-\frac{c}{k^{2/3}}}(c_{1}\log x)^{k}),
$$
where
$c>0$,
$c_1>0$ — are absolute constants.
Let
$\mathbb{N}_{0}$ — be a set of natural numbers whose binary expansions have even number of ones.
In 1991, the autor [8] solved Dirichlet divisors problem and got the formula
$$
\sum_{\substack{n\leqslant X\\ n\in \mathbb{N}_{0}}}\tau(n)=\frac{1}{2}\sum_{n\leqslant X}\tau(n)+O(X^{\omega }\ln^{2}X),
$$
where
$\tau(n)$ — the number of divisors
$n$, $\omega=\frac{1}{2}\big(1+\log_{2}\sqrt{2+\sqrt{2}}\big)=0.9428\ldots$.
In this paper, we solve the generalyzed Dirichlet divisors problem in numbers from
$\mathbb{N}_{0}$.
Bibliography: 15 titles.
Keywords:
generalized problem of divisors, binary expansions, asymptotic formula, uniform estimate of the remainder term.
UDC:
511 Received: 18.12.2015
Accepted: 11.03.2016