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Questions where prime numbers play a key-role, such as: questions on the distribution of prime numbers (twin primes, gaps between primes, Hardy–Littlewood conjectures, etc); questions on prime numbers with special properties (Wieferich prime, Wolstenholme prime, etc.). This tag is often used as a specialized tag in combination with the top-level tag nt.number-theory and (if applicable) analytic-number-theory.

11 votes
1 answer
926 views

Riemann sum formula for definite integral using prime numbers

I had asked this question in MSE. It got lot of upvotes but no answer (except one which was too long to be posted as a comment) hence I am posting it in MO. While answering another question in MSE I …
Nilotpal Kanti Sinha's user avatar
2 votes
0 answers
131 views

How many divisors of $\phi(m)$ do not divide $m-1$?

Lehmer's totient problem asks if there exists a composite number $m$ such that $\phi(m)$ divides $m-1$. Lower bounds on $m$ has been established but we do not know if a solution exists. Clearly, if we …
Nilotpal Kanti Sinha's user avatar
4 votes
2 answers
699 views

On a sum involving prime numbers

I find myself needing the asymtotics of the following summation for my work. Let $a$ be a positive real number and $p_n$ be the $n$-th prime. $$ \sum_{k=1}^{n} [k^a - (k-1)^a]p_k $$ At $a=1$, this …
Nilotpal Kanti Sinha's user avatar
6 votes
3 answers
759 views

A simple looking problem in partitions that became increasingly complex

I began with problem which looked simple in the beginning but became increasingly complex as I dug deeper. Main questions: Find the number of solutions $s(n)$ of the equation $$ n = \frac{k_1}{1} + …
Nilotpal Kanti Sinha's user avatar
3 votes
3 answers
803 views

Mathematical techniques to reduce the amount of storage memory

Apologies for the length question. Those acquainted with the analytics industry will know that the next big thing in the information technology world will be the Big Data revolution where huge volumes …
Nilotpal Kanti Sinha's user avatar
23 votes
1 answer
3k views

Does the average primeness of natural numbers tend to zero?

This question was posted in MSE. It got many upvotes but no answer hence posting it in MO. A number is either prime or composite, hence primality is a binary concept. Instead I wanted to put a valu …
Nilotpal Kanti Sinha's user avatar
5 votes
0 answers
89 views

Is the ratio of a number to the variance of its divisors injective?

The variance $v_n$ of a natural number $n$ is defined as the variance of its divisors. There are distinct integer whose variances are equal e,g. $v_{691} = v_{817}$. However I observed that for $n \le …
Nilotpal Kanti Sinha's user avatar
3 votes
0 answers
322 views

If $p^2 - q^2$ is a perfect square where $p$ and $q$ are primes $> 5000$ then is one of its ... [closed]

Is it true that if $p^2 - q^2$ is a perfect square where $p$ and $q$ are primes $> 5000$ then it has a prime factor greater than $17$? Note: This question was asked in MSE but did not receive an answ …
Nilotpal Kanti Sinha's user avatar
1 vote
0 answers
133 views

Primes which do not divide certain homogeneous polynomials

It is known that if $x^2 + y^2 = z^2$ is a primitive Pythagorean triplet then $z$ is not divisible by any prime of the form $4k-1$. The following is a generalization of this classical result which sh …
Nilotpal Kanti Sinha's user avatar
6 votes
4 answers
2k views

Probability that randomly chosen integers from a restricted set of natural numbers are coprime

We know that the probability $P(k)$ of $k$ randomly chosen integers $(k \ge 2)$ from the set of natural number are coprime is $$ P(k) = \frac{1}{\zeta(k)}. $$ I am looking at a special case of thi …
Nilotpal Kanti Sinha's user avatar
8 votes
1 answer
826 views

Are there highly composite prime gaps?

Definition: Highly composite prime gap The three composite numbers between the consecutive primes $643$ and $647$ each have at least three distinct prime factors. This is the first occurrence of prime …
Nilotpal Kanti Sinha's user avatar
5 votes
1 answer
958 views

There at least 4 divisors of $n-1$ which do not divide $\phi(n)$ if $n$ is a composite of th...

If $n$ is composite then $\phi(n) < n-1$ (Euler's totient function) hence there must be one or more divisors of $n-1$ which do not divide $\phi(n)$. For lack of a better terminology, let us call these …
Nilotpal Kanti Sinha's user avatar
7 votes
0 answers
274 views

Are there infinitely many zeroes of $\sum_{r = 1}^{n-1} \mu(r)\gcd(n,r) $?

Let $\mu(n)$ be the Möbius function and $S(x)$ be the number of positive integers $n \le x$ such that $$ \sum_{r = 1}^{n-1} \mu(r)\gcd(n,r) = 0 $$ My experimental data for $n \le 6 \times 10^5 $se …
Nilotpal Kanti Sinha's user avatar
11 votes
1 answer
434 views

How many numbers $\le x$ can be factorized into three numbers which form the sides of a tria...

Note: Posting in MO since it was unanswered in MSE Definition: We say that a natural number $n$ has triangular divisors if it has at least one triplet of divisors $n = d_1d_2d_3, 1 \le d_1 \le d_2 \l …
Nilotpal Kanti Sinha's user avatar
6 votes
6 answers
2k views

Sequences equidistributed modulo 1

Let $\alpha$ be any positive irrational and $\beta$ be any positive real. We have the following results. H. Weyl (1909): The fractional part of the sequence $\alpha n$ is equidistributed modulo 1. I …
Nilotpal Kanti Sinha's user avatar

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