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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.

21 votes
4 answers
1k views

Are there open problems for primes which are known for probable primes?

Define "probable prime" (PP) to be natural $n>1$ satisfying $2^{n-1} \equiv 1 \pmod{n}$ or $n=2$. Probable primes are the union of the primes and base two pseudoprimes. This definition is much simpl …
joro's user avatar
  • 25.4k
11 votes
0 answers
1k views

Are the twin primes the only positive double zeros of this real function?

Agno's answer was extremely helpful. For $x \in \mathbb{R}, x \ge 1$ define $$ f(x) = \sin\frac{\pi(\Gamma(x)+1)}{\lfloor x \rfloor}$$ By Wilson's theorem the positive integer zeros of $f(x)$ are ex …
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  • 25.4k
10 votes
4 answers
1k views

The smallest solution to $2^{2k}-1=\text{powerful}$

Integer is powerful if all the exponents in its factorization are at least $2$. Every powerful integer can be written in the form $a^2 b^3$. For odd $k$, define $F(k)=2^{2k}-1=(2^k-1)(2^k+1)$. This pa …
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  • 25.4k
7 votes
2 answers
870 views

Unexpectedly prime rich cubic polynomial

We got a cubic polynomial which is unexpectedly prime rich. Let $f(x)=29160 x^3 + 30132 x^2 + 8046 x + 643$ and $\pi_f(n)$ the number of primes values of $f(x)$ for $x \in [1,n]$. Let $F(n)=\frac{\ …
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  • 25.4k
7 votes
2 answers
676 views

What is wrong with this deterministic algorithm efficiently generating large primes?

According to PolyMath (Strong) conjecture. There exists deterministic algorithm which, when given an integer k, is guaranteed to find a prime of at least k digits in length of time polynomial in k …
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  • 25.4k
6 votes
2 answers
793 views

Must Mersenne numbers be divisible by arbitrary large primes with exponent one?

Let $M_n$ denote the Mersenne numbers $M_n=2^n-1$. As $n$ varies, must $M_n$ be divisible by arbitrary large prime $p$ with exponent one, i.e. $p \mid M_n, p^2 \nmid M_n$? In other words, must the exp …
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  • 25.4k
5 votes
1 answer
363 views

Prime race modulo $12$. When is the first sign change?

Define $\pi(x;q,a)$ as the number of primes less than or equal to $x$ which are congruent to $a$ modulo $q$. Up to $x=10^{11}$ we have $\pi(x;12,1) \le \pi(x;12,-1)$. What is the smallest $x$ for wh …
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  • 25.4k
5 votes
0 answers
160 views

Reducibility of $f(x)^{2^n}+1$ and $f(x)^{2^n}+g(x)^{2^n}$

Related to generalized Fermat numbers. Let $f(x),g(x)$ be coprime polynomials with integer coefficients. Assume that if $f(x)$ or $g(x)$ are of the form $h(x)^k$ then $k$ is power of two. Q1 Is it po …
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  • 25.4k
5 votes
1 answer
722 views

Sum of two squares and implication of Bunyakovsky conjecture

Bunyakovsky's conjecture states that a polynomial with integer coefficients takes infinitely many prime values at integers, unless this is impossible for trivial reasons. Let $a_1(x), a_2(x), a_3(x), …
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  • 25.4k
5 votes
2 answers
455 views

Function with zeros plus/minus the primes

While playing with Cohen's pari script prodeulerrat found a function. For $s \in \mathbb{C}$ define $$ f(s) = \prod_{p \text{ prime}} (1-\frac{s^2}{p^2})$$ The product converges everywhere, no poles a …
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  • 25.4k
5 votes
1 answer
163 views

On vanishing of $p$-adic logarithms

Might be related to Wieferich primes. Let $p$ be odd prime and define the Fermat quotient $$F(n)=\frac{(2^{n-1} -1)}{n} \mod n=\frac{(2^{n-1} \bmod n^2 )-1}{n}$$ For integer $b$ let $L_p(b)$ be the $p …
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  • 25.4k
4 votes
2 answers
460 views

Small $|2^x 3^y - 5^z 7^t|$ and generalization

Let $\{p_i\},\{q_i\}$ be disjoint sets of primes. For natural $e_i,f_i$ define $A=\prod p_i^{e_i},B=\prod q_i^{f_i}$. Is it true that for all real $d < 1$, $|A-B| < \max(A,B)^d$ has finitely many sol …
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  • 25.4k
4 votes
2 answers
856 views

Can a polynomial be almost always divisible by a member of a finite set of primes?

Special case of Bunyakovsky conjecture Let $f(x)$ be non-constant irreducible polynomial with integer coefficients, no fixed prime factor and positive leading coefficient. Let $S$ be a finite set of …
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  • 25.4k
4 votes
0 answers
187 views

Small solutions of $f(x_1,...,x_n) \equiv 0 \pmod p$

Let $f(x_1,...,x_n)$ be polynomial with integer coefficients. Is the following possible: For almost all primes $p$ exist integers $X_1,...,X_n$ such that: $f(X_1,...,X_n) \ne 0$ $f(X_1,...,X_n) \equi …
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  • 25.4k
4 votes
2 answers
648 views

Conjectured relation between alternating Prime zeta series and Riemann zeta

Let $P(s)$ be the Prime zeta function. Numerical evidence suggests these identities: $$ \sum_{k=1}^\infty \frac{(-1)^{k}P(3k)}{k}=\log{\bigg(\frac{1}{945}\frac{\pi^6}{\zeta(3)}\bigg)}\qquad\quad (1) …
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