Symbols:D/Derangements

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Derangement

$D_n$ or $d_n$

A derangement is a permutation $f: S \to S$ from a set $S$ to itself where:

$\forall s \in S: \map f s \ne s$

That is, a permutation with no fixed points.


If $S$ is finite, the number of derangements is denoted by $D_n$ or $d_n$, where $n = \card S$ (the cardinality of $S$.)


The $\LaTeX$ code for \(D_n\) is D_n .

The $\LaTeX$ code for \(d_n\) is d_n .


Sources