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Results tagged with prime-numbers
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user 12858
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.
7
votes
2
answers
1k
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Recovering n from sigma(n)/n
For any positive integer $n$, we define
$$\sigma(n) := \sum_{d \mid n} d,$$
and
$$\delta(n) := \frac{\sigma(n)}{n} = \sum_{d \mid n} \frac{1}{d}.$$
Is there an (efficient) way to determine $\delta^{-1 …
- 6,614
6
votes
Accepted
Conjecture on prime numbers
This is related to Linnik's theorem:
http://en.wikipedia.org/wiki/Linnik%27s_theorem . See in particular the conjecture on this wikipedia page:
It is also conjectured that: $p(a,d) < d^2$,
where …
- 6,614
4
votes
The prime number $2$
There are many possible answers to this question, and it depends a lot on the context, but certainly one of the main reasons is that you cannot distinguish between $1$ and $-1$ modulo $2$, whereas $1 …
- 6,614