ترغب بنشر مسار تعليمي؟ اضغط هنا

On a sum involving certain arithmetic functions and the integral part function

173   0   0.0 ( 0 )
 نشر من قبل Huayan Sun
 تاريخ النشر 2021
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

In this short, we study sums of the shape $sum_{nleqslant x}{f([x/n])}/{[x/n]},$ where $f$ is Euler totient function $varphi$, Dedekind function $Psi$, sum-of-divisors function $sigma$ or the alternating sum-of-divisors function $beta.$ We improve previous results when $f=varphi$ and derive new estimates when $f=Psi, f=sigma$ and $f=beta.$

قيم البحث

اقرأ أيضاً

108 - Kui Liu , Jie Wu , Zhishan Yang 2021
Denote by $tau$ k (n), $omega$(n) and $mu$ 2 (n) the number of representations of n as product of k natural numbers, the number of distinct prime factors of n and the characteristic function of the square-free integers, respectively. Let [t] be the i ntegral part of real number t. For f = $omega$, 2 $omega$ , $mu$ 2 , $tau$ k , we prove that n x f x n = x d 1 f (d) d(d + 1) + O $epsilon$ (x $theta$ f +$epsilon$) for x $rightarrow$ $infty$, where $theta$ $omega$ = 53 110 , $theta$ 2 $omega$ = 9 19 , $theta$ $mu$2 = 2 5 , $theta$ $tau$ k = 5k--1 10k--1 and $epsilon$ > 0 is an arbitrarily small positive number. These improve the corresponding results of Bordell{`e}s.
We obtain reasonably tight upper and lower bounds on the sum $sum_{n leqslant x} varphi left( leftlfloor{x/n}rightrfloorright)$, involving the Euler functions $varphi$ and the integer parts $leftlfloor{x/n}rightrfloor$ of the reciprocals of integers.
We define a new parameter $A_{k,n}$ involving Ramanujans theta-functions for any positive real numbers $k$ and $n$ which is analogous to the parameter $A_{k,n}$ defined by Nipen Saikia cite{NS1}. We establish some modular relation involving $A_{k,n}$ and $A_{k,n}$ to find some explicit values of $A_{k,n}$. We use these parameters to establish few general theorems for explicit evaluations of ratios of theta functions involving $varphi(q)$.
Let $mathcal{S}$ denote the family of all functions that are analytic and univalent in the unit disk $mathbb{D}:={z: |z|<1}$ and satisfy $f(0)=f^{prime}(0)-1=0$. In the present paper, we consider certain subclasses of univalent functions associated w ith the exponential function, and obtain the sharp upper bounds on the initial coefficients and the difference of initial successive coefficients for functions belonging to these classes.
By $(mathbb{Z}^+)^{infty}$ we denote the set of all the infinite sequences $mathcal{S}={s_i}_{i=1}^{infty}$ of positive integers (note that all the $s_i$ are not necessarily distinct and not necessarily monotonic). Let $f(x)$ be a polynomial of nonne gative integer coefficients. Let $mathcal{S}_n:={s_1, ..., s_n}$ and $H_f(mathcal{S}_n):=sum_{k=1}^{n}frac{1}{f(k)^{s_{k}}}$. When $f(x)$ is linear, Feng, Hong, Jiang and Yin proved in [A generalization of a theorem of Nagell, Acta Math. Hungari, in press] that for any infinite sequence $mathcal{S}$ of positive integers, $H_f(mathcal{S}_n)$ is never an integer if $nge 2$. Now let deg$f(x)ge 2$. Clearly, $0<H_f(mathcal{S}_n)<zeta(2)<2$. But it is not clear whether the reciprocal power sum $H_f(mathcal{S}_n)$ can take 1 as its value. In this paper, with the help of a result of ErdH{o}s, we use the analytic and $p$-adic method to show that for any infinite sequence $mathcal{S}$ of positive integers and any positive integer $nge 2$, $H_f(mathcal{S}_n)$ is never equal to 1. Furthermore, we use a result of Kakeya to show that if $frac{1}{f(k)}lesum_{i=1}^inftyfrac{1}{f(k+i)}$ holds for all positive integers $k$, then the union set $bigcuplimits_{mathcal{S}in (mathbb{Z}^+)^{infty}} { H_f(mathcal{S}_n) | nin mathbb{Z}^+ }$ is dense in the interval $(0,alpha_f)$ with $alpha_f:=sum_{k=1}^{infty}frac{1}{f(k)}$. It is well known that $alpha_f= frac{1}{2}big(pi frac{e^{2pi}+1}{e^{2pi}-1}-1big)approx 1.076674$ when $f(x)=x^2+1$. Our dense result infers that when $f(x)=x^2+1$, for any sufficiently small $varepsilon >0$, there are positive integers $n_1$ and $n_2$ and infinite sequences $mathcal{S}^{(1)}$ and $mathcal{S}^{(2)}$ of positive integers such that $1-varepsilon<H_f(mathcal{S}^{(1)}_{n_1})<1$ and $1<H_f(mathcal{S}^{(2)}_{n_2})<1+varepsilon$.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا