Difference between revisions of "Möbius"

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File:Mobiusmuplot,n=0..100.png|Plot of $\mu$ for $n=0,\ldots,100$.
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File:Mobiusplot,on0to40.png|Graph of $\mu$ on $[0,40]$.
File:Mobiusmuplot,n=0..500.png|Plot of $\mu$ for $n=0,\ldots,500$.
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File:Mobiusplot,on0to100.png|Graph of $\mu$ on $[0,100]$.
 
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Revision as of 09:43, 16 June 2016

The Möbius function is the function $\mu$ defined by the formula $$\mu(n) = \left\{ \begin{array}{ll} 1 &; n \mathrm{\hspace{2pt}is\hspace{2pt}a\hspace{2pt}squarefree\hspace{2pt}positive\hspace{2pt}integer\hspace{2pt}with\hspace{2pt}even\hspace{2pt}number\hspace{2pt}of\hspace{2pt}prime\hspace{2pt}factors} \\ -1 &; n \mathrm{\hspace{2pt}is\hspace{2pt}a\hspace{2pt}squarefree\hspace{2pt}positive\hspace{2pt}integer\hspace{2pt}with\hspace{2pt}odd\hspace{2pt}number\hspace{2pt}of\hspace{2pt}prime\hspace{2pt}factors} \\ 0 &; n\mathrm{\hspace{2pt}has\hspace{2pt}a\hspace{2pt}square\hspace{2pt}divisor}. \end{array} \right.$$


Properties

Theorem: If $s \in \mathbb{C}$ with $\mathrm{Re}(s) > 1$, then $$\displaystyle\sum_{n=1}^{\infty} \dfrac{\mu(n)}{n^s} = \dfrac{1}{\zeta(s)},$$ where $\zeta$ is the Riemann zeta function.

Proof:

Relationship between prime zeta, Möbius function, logarithm, and Riemann zeta

Videos

Mobius Function Example
Möbius Function - Introduction
Möbius Function - Merten's function
Number Theory 27: Mobius function is multiplicative