Number of Primes between two integers


by Cheung
Tags: counting, formula, function, integers, number, primes
Cheung
Cheung is offline
#1
Nov10-13, 09:02 PM
P: 3
Is there a formula to calculate the EXACT number of primes between two integers? There are many very good ways of ESTIMATING the number but I have found very few that give the EXACT number, and those that do essentially require the knowledge of primes before hand (Legendre and Miessel.) While those are all nice I am looking for a formula (not an algorithm) that will spit out the EXACT number of primes by knowing only the two boundaries. Has it been done?
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goldust
goldust is offline
#2
Nov10-13, 09:11 PM
P: 85
Exact? No. But as the numbers in question approach infinity, they behave more accordingly to the Prime Number Theorem.
jbriggs444
jbriggs444 is offline
#3
Nov12-13, 09:11 AM
P: 748
With the use of pi(n) you could easily construct a forumula for the number of primes between two integers i and j. However, I imagine that you would classify pi(n) as being an "algorithm" rather than a "formula".

http://mathworld.wolfram.com/PrimeCountingFunction.html

Cheung
Cheung is offline
#4
Nov13-13, 09:15 PM
P: 3

Number of Primes between two integers


Thank you both for your reply's and to jbriggs444 I would consider using the logarithmic pi(x) an algorithm. I am looking for a formula/ function that would shed more light on the distribution of primes by solving for the number of primes using only the two integer limits.


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