Definition:Noncototient

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Definition

A noncototient is a positive integer $n$ such that:

$\nexists m \in \Z_{>0}: m - \phi \left({m}\right) = n$

where $\phi \left({m}\right)$ denotes the Euler $\phi$ function.


That is, a noncototient is a positive integer which is not the cototient of any positive integer.


Sequence

The sequence of noncototients begins:

$10, 26, 34, 50, 52, 58, 86, 100, 116, 122, 130, 134, 146, 154, 170, 172, 186, 202, \ldots$


Also see


Sources