Difference between revisions of "Euler totient"

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=References=
 
=References=
 
[http://dualaud.net/specialfunctionswiki/abramowitz_and_stegun-1.03/page_826.htm Abramowitz&Stegun]
 
[http://dualaud.net/specialfunctionswiki/abramowitz_and_stegun-1.03/page_826.htm Abramowitz&Stegun]
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[[Category:SpecialFunction]]

Revision as of 18:48, 24 May 2016

Euler's totient function is the function

$\phi(n) =$ # of positive integers $\leq n$ that are relatively prime to $n$.

Properties

Theorem: The function $\phi$ obeys the formula $$\phi(n) = \displaystyle\sum_{d|n} \mu(d) \dfrac{n}{d},$$ where the notation $d | n$ indicates that $d$ is a divisor of $n$ and $\mu$ is the Möbius function.

Proof:

Theorem: The function $\phi$ obeys the formula $$\phi(n) = n \displaystyle\prod_{p | n} \left( 1 - \dfrac{1}{p} \right),$$ where the notation $p | n$ indicates that $p$ is a prime that divides $n$.

Proof:

Theorem: The following formula holds: $$\phi(n) = n\lim_{s \rightarrow 1} \zeta(s) \displaystyle\sum_{d | n} \mu(d)(e^{\frac{1}{d}})^{s-1},$$ where $\zeta$ is the Riemann zeta function and $\mu$ is the Möbius function, $e$ is the base of the exponential and the notation $d|n$ indicates that $d$ is any divisor of $n$.

Proof:

Videos

Euler's Totient Function: what it is and how it works
Euler's Totient Theorem: What is Euler's Totient Theorem and Why is it useful?
Euler's Totient Function | How To Find Totient Of A Number Using Euler's Product Formula
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Application of Euler Totient Function Part 16
Möbius and Euler totient functions
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03 Modern cryptography 08 Euler's totient function

References

Abramowitz&Stegun