Does an Extension of the Primorial Function Exist?

  • Context: Graduate 
  • Thread starter Thread starter quinn
  • Start date Start date
  • Tags Tags
    Function
Click For Summary

Discussion Overview

The discussion centers around the Primorial function, denoted as n#, which represents the product of all prime numbers less than or equal to n. Participants explore the potential for an extension of the Primorial function, drawing comparisons to the gamma and factorial functions, and examining its asymptotic behavior and relationships to other mathematical concepts.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant wonders if there exists an extension to the Primorial function similar to the recursive relationship found in the gamma/factorial function.
  • Another participant mentions a simple asymptotic for the logarithm of the Primorial function, suggesting that log(n#) is approximately equal to n, based on a form of the prime number theorem.
  • A different perspective introduces the Chebyshev function, θ(x), and relates it to the logarithm of the Primorial function, indicating that log(p#) can be approximated as n log n using this definition.
  • It is noted that p# is approximately e^p, with a reference to Pierre Dusart's work that provides tight bounds for this and related functions concerning prime counting.

Areas of Agreement / Disagreement

Participants present various viewpoints and mathematical relationships regarding the Primorial function, but there is no consensus on the existence of an extension or the implications of the discussed asymptotic behaviors.

Contextual Notes

The discussion includes assumptions related to the definitions of the functions involved and the applicability of the prime number theorem, which may not be universally accepted or resolved within the context of this thread.

quinn
Messages
44
Reaction score
0
I only am wondering about the Primorial function, n#, (product of all primes less than or equal to n)

The gamma/factorial function has a nice recursive relationship that is composed of elementary functions; does there exsist an extension to the primorial function?
 
Physics news on Phys.org
There's a simple asymptotic for it's logarithm given by one form of the prime number theorem, log(n#)~n.
 
If you define the Chebyshev function:

[tex]\theta (x)= \sum_{p<x} log(p)[/tex] then:

[tex]\theta (p_{n}) = log(p#)[/tex] but using this definition the PNT gives

[tex]log(p # ) \sim nlogn[/tex]
 
p# is about [itex]e^p[/itex]. Pierre Dusart has a paper with fairly tight bounds for this and other functions relating to prime counting.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
7K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 12 ·
Replies
12
Views
1K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 14 ·
Replies
14
Views
5K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K