2
votes
0answers
63 views

Interchanging limits with the prime counting function

How does one justify that $$\lim_{s \to 1} \lim_{x \to \infty} \frac{\pi(x)}{x^s} = \lim_{x \to \infty} \lim_{s \to 1} \frac{\pi(x)}{x^s}, \quad s > 1,$$ without using the fact that the primes have ...
2
votes
1answer
30 views

Extrema of the Ratio of Consecutive Primes

Let $p_i$ denote the $i$th prime number. We know that $\frac{p_{n+1}}{p_n}\rightarrow 1$ as $n\rightarrow\infty$. Therefore, if we pick some real number $c>1$, there should be some positive integer ...
1
vote
0answers
47 views

Prime Zeta Function

Does $$\sum_{p \text{ prime}} \frac{1}{p^s} \sim \log \zeta(s) \quad \text{as} \quad s \to 1^+$$ imply $$\sum_{p \leq n} \frac{1}{p} \sim \log H_n \quad \text{as} \quad n \to \infty,$$ where $H_n$ is ...
1
vote
1answer
42 views

Asymptotic behavior of $\pi (x)-\frac{x}{\log x}$

What is the asymptotic behavior of the function given below. $$f(x)=\pi (x)-\frac{x}{\log x}$$ $$f(x)=O(g(x))$$ What can be $g(x)$? Also what is the asymptotic behavior of the $h(x)=f(x)-g(x)$. My ...
4
votes
1answer
80 views

On the sum of prime powers

Has anybody investigated the asymptotic growth rate of functions in the form of $$f(z,n)=\sum\limits_{p\le n}p^z$$ For $Re(z)\ge -1$. Of course $f(0,n)=\pi (n)$ has an ocean of research surrounding ...
1
vote
1answer
141 views

A question about prime gaps

Recently, I have been reading the Wikipedia article about prime gaps (http://en.wikipedia.org/wiki/Prime_gap) and I came across the following: Hoheisel was the first to show that there exists a ...
4
votes
0answers
59 views

prime zeta function when $0<s<1$ [duplicate]

I would like to know if there is a good estimate for the sum which concerns all primes not exceeding $x$: $$\sum\limits_{p\leq x}\frac{1}{p^s}$$$$0<s<1$$. Only this. Thanks in advance!
3
votes
1answer
140 views

Explanation for Terry T. post

I read here that : " If one inserts these inequalities into the Legendre sieve and optimises the parameter, one can improve the upper bound for the number of primes in $[N,2N]$ to $$O \left(\frac{N ...
3
votes
1answer
98 views

Bound of the sum $\sum_{p\le n}\frac{1}{\log(p)}$

While doing a sum I came to the sum $\displaystyle\sum_{p\le n}\dfrac{1}{\log(p)}$. Where the $\log$ is the natural logarithm. It was easy to prove that $\displaystyle\sum_{p\le ...
1
vote
0answers
41 views

Asymptotics for prime factors

Am I correct in assuming that the same result: $$ N_k(x):=\ \mid\{n\leq x : \Omega(n)=k\}\mid \ \sim \frac{x}{\log x}\frac{(\log_2 x)^{k-1}}{(k-1)!}\ (x \rightarrow \infty) $$ also holds for: $$ ...
7
votes
1answer
178 views

Asymptotic formula for almost primes

I have developed a formula for almost primes which is far more accurate asymptotically than Landau's well known $$\pi_k(n) \sim \left( \frac{n}{\log n} \right) \frac{(\log\log n)^{k-1}}{(k - 1)!}$$ ...
1
vote
1answer
68 views

$\pi(x)$ asymptotic as integral $1/\log t$

From the prime number theorem we know that $\pi(x)\sim x/\log x$, i.e. $\dfrac{\pi(x)\log x}{x}\rightarrow 1$ as $x\rightarrow \infty$. How can we use that to show that ...
0
votes
0answers
56 views

Can we find the relation between $2^n$ and the $m$th primorial

I'm looking for a positive real $n$, given positive real $m>2$. The calculations for $n$ proceed according to the following diagram: $$ \begin{array}{ccc} m & \rightarrow & 2^m \\ & ...
4
votes
0answers
149 views

Understanding Newman's proof of the prime number theorem

I am trying to understand D.J. Newman's proof of the prime number theorem, as presented by D. Zagier. I am not too familiar with analysis, and so there are some things I don't understand. In (III), ...
4
votes
2answers
345 views

Using sum of logarithms of primes to prove the number of primes up to $n$ is $O(n/\log n)$

I need to show that the number of primes up to $n$ (i.e. $\pi(n)$) is $O(n/\log n)$. In the previous exercise of this question I proved that ${\displaystyle \sum_{i=1}^{\pi(n)}\log p_{i}} \leq Cn$ for ...
0
votes
1answer
145 views

Ratio of primes $(x^2+x+(5+6m))$ to $(x^2+x+(3+6m))$

What I did: For a large n and $x\leq n$ I counted the number of primes of the form $x^2+x+(5+6m)$ for $m = 0, 1, 2, 3,..., n/2,$ added the number of primes for each m together and called the sum A. ...
0
votes
0answers
57 views

Are the Prime Numbers $O(f(n))$ where $f(n)$ is some polynomial?

Are the prime number, denoted $ p(n) $, $O(f(n))$, for any polynomial $f(n)$?
3
votes
1answer
123 views

What happened to the Mertens constant in the strong prime twins conjecture ??

To estimate the amount of primes in an interval $\left(2,x\right)$ one might naively sieve by computing $ x \left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)...\left(1-\dfrac{1}{p_i}\right)$ ...
1
vote
1answer
89 views

$x \sim y \implies \pi(x) \sim \pi(y) $ and repeated applications of PNT

Let $\sim$ mean if $a \sim b$ then $\lim_{x \to \infty} \frac{a}{b} =1.$ The following is a threshold question. It seems that $x \sim y \implies \pi(x) \sim \pi(y).$ Pf. $\pi(x) \sim \frac{x}{\log ...
4
votes
1answer
76 views

Asymptotics with prime of form 4k+3

I wonder if there is some asymptotics for such sum: $ \sum_{p=2}^{n} \frac{1}{p}$, where the sum is taken over all primes of form $ 4k+3 $? It's well-known that $ \sum_{p=2}^{n} \frac{1}{p}$, where ...
4
votes
2answers
239 views

Is there a function that only generates primes?

The title sums it up: does there exist a "nice" injective function $f(n)$ such that $f(n)\in\mathbb P$ for all $n\in\mathbb N$? I'm having difficulty specifying exactly what I want "nice" to mean, ...
1
vote
0answers
131 views

Approximation of distribution of $\pi_k(n)$ using $\zeta(s)$

Let $\pi_k(n) $ be the number of numbers with k prime factors (repetitions included) less than or equal to n. If we take the sums: $z_1(s) = \sum_{n= 1}^\infty \frac{1}{(p_{1,n})^s},~ z_2(s) = \sum ...
2
votes
1answer
296 views

Why is $\pi$ the Limit of the Absolute Value of the Prime $\zeta$ Function?

Motivation: I was looking at the approximation of the truncated Prime $\zeta$ function $$ P_x(s)=\sum_{p\leq x}p^{-s}= \mathrm{li}(x^{1-s}) + O \left(\cdot \right) $$ (to be found here with or ...
25
votes
1answer
756 views

How many primes does Euclid's proof account for?

This is a passing curiosity, and I haven't found any duplicates, so I thought I'd share my thoughts. In the most basic (or at least the most famous) proof of the infinitude of prime numbers, due to ...
4
votes
2answers
116 views

Asymptotics of products of primes

Let $P(n)=\{p \leq n: p\text{ is prime} \}$. For given $N$ and $n$, what's a good approximation for $|S(N,n)|$, where $S(N,n)=\{x<N: \forall p\text{ prime, s.t. }p|x \to p \in P(n) \}$. In other ...
3
votes
1answer
242 views

(Not) Surprising Result on Natural Numbers as Sum of $k$-Almost Primes

I started with the following idea: Let $P_k$ be the infinte set of all $k$-almost primes. The counting function for $k$-almost primes less than $x$, is $\displaystyle \pi_k(x)\sim\frac{x}{\log ...
9
votes
3answers
545 views

Equivalence to the prime number theorem

I was just reading this question and answer: How will this equation imply PNT and it raised a whole new question: Given that $\sum_{n\le x} \Lambda(n)=x+o(x)$, prove that $$\sum_{n\le x} ...
11
votes
2answers
416 views

Asymptotics of LCM

Let $\operatorname{LCM}(x_1,x_2,\ldots,x_n)$ be the least common multiple of the integers $x_i$. How can one find the asymptotics of $\operatorname{LCM}(f(1),f(2),\dots,f(n))$ as $n$ approaches ...
5
votes
0answers
192 views

Sums of Dirichlet-Characters over prime numbers (part 2)

This is kind of related to my previous question that was poorly stated because of misreading my own notes that I have taken on the papers I am currently reading, so no surprise that it eventually ...
27
votes
3answers
529 views

Sequence of numbers with prime factorization $pq^2$

I've been considering the sequence of natural numbers with prime factorization $pq^2$, $p\neq q$; it begins 12, 18, 20, 28, 44, 45, ... and is A054753 in OEIS. I have two questions: What is the ...
0
votes
2answers
440 views

Estimate the average number of prime factors of a 1000-digit number

More formally, find an asymptotic for $N\to\infty$ of $$\frac{\sum_{1\le k\le N} M(k)}{N}$$ where $$M(p_1^{d_1}p_2^{d_2}\cdots p_k^{d_k}) = d_1+d_2+\cdots+d_k$$ For example, $M(24) = M(2^3\cdot3) = ...