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3 votes
1 answer
163 views

Increasing sequences and Wieferich primes

We are trying to show that primes of the form $a(n)$ can't be Wieferich primes. For natural $n$ define $J(n)=(2^{n-1}-1) \bmod n^2$ and if $n$ is power of two define $J(2^n)=1$ (this is artificial, ...
joro's user avatar
  • 25.4k
2 votes
0 answers
93 views

Primes of the form $a+b^k$ for $k=(a \bmod 2),\ldots,n$?

Procrastinal problem: Given $n$, one can ask for integers $a,b>1$ of different parities such that $a+b^k$ is prime for $k=(a\bmod 2),\ldots,n$. A few examples are: $2+4995825^k$ is prime for $k=0,\...
Roland Bacher's user avatar
1 vote
0 answers
376 views

Astonishing affinity of Wolfram's rule 110 to the numbers 2 and 7

I investigated the evolution of a single black cell on 1-dimensional grids with periodic boundary conditions of variable sizes $N$ under Wolfram's rule 110 which is the only one for which Turing ...
Hans-Peter Stricker's user avatar
6 votes
0 answers
479 views

Existence of an explosive prime

The motivation to introduce explosive prime is Carmichael's totient conjecture (see why below). Let $\mathbb{N}_{SF}$ be the set of positive square-free integers. Consider the map $f:\mathbb{N}_{SF} \...
Sebastien Palcoux's user avatar
0 votes
1 answer
492 views

New experiments involving Ramanujan primes: Benford's law

I know that in the literature there are interesting articles involving the sequence of Ramanujan primes, I refer the Ramanujan Prime from the online encyclopedia Wolfram MathWorld. This week I ...
user142929's user avatar
5 votes
1 answer
354 views

Gadgets as primality tests

From the literature, showed below, I know two gadgets that provide a way to know if a positive integer (a positive quantity of units) is composite or a prime number. I would like to know if in the ...
user142929's user avatar
9 votes
3 answers
2k views

May $p^3$ divide $(a+b)^p-a^p-b^p$?

Do there exist positive integers $a,b$ and a prime $p>\max(a,b)$ such that $p^3$ divides $(a+b)^p-a^p-b^p$? The reader of Kvant magazine A. T. Kurgansky asked to prove that such $a,b,p$ do not ...
Fedor Petrov's user avatar
2 votes
0 answers
237 views

On the cardinality of the set of right-truncatable primes

We say that the (base ten) prime number $p=a_{n}a_{n-1}a_{n-2}\cdots a_{1}a_{0}$ is right-truncatable if all of the following numbers are prime: \begin{eqnarray*}a_{n},\\a_{n}a_{n-1},\\ a_{n}a_{n-1}...
José Hdz. Stgo.'s user avatar
5 votes
1 answer
1k views

Lines in image; are they significant to prime numbers if so how?

Amateur math question. I was playing around generating some 2D images, and wondered what it would look like if placed $P_{i}$ dots on a circle with diameter of $i$ for increasing values of $i$, where $...
spinkus's user avatar
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