Difference between revisions of "Euler's phi function"

 
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'''Euler's phi function''' determines the number of integers less than a given positive integer that are [[relatively prime]] to that integer.
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#REDIRECT [[Euler's totient function]]
 
 
=== Formulas ===
 
 
 
Given the [[prime factorization]] of <math>{n} = {p}_1^{e_1}{p}_2^{e_2} \cdots {p}_n^{e_n}</math>, then one formula for <math>\phi(n)</math> is <math> \phi(n) = n\left(1-\frac{1}{p_1}\right)\left(1-\frac{1}{p_2}\right) \cdots \left(1-\frac{1}{p_n}\right) </math>.
 
 
 
=== Identities ===
 
 
 
For [[prime]] p, <math>\phi(p)=p-1</math>, because all numbers less than <math>{p}</math> are relatively prime to it.
 
 
 
For relatively prime <math>{a}, {b}</math>, <math> \phi{(a)}\phi{(b)} = \phi{(ab)} </math>.
 
 
 
=== See also ===
 
 
 
* [[Number theory]]
 
* [[Prime]]
 
* [[Euler's Totient Theorem]]
 

Latest revision as of 14:36, 18 June 2006