\begin{definition}[Definition:Noncototient/Sequence]
The sequence of '''noncototients''' begins:
:$10, 26, 34, 50, 52, 58, 86, 100, 116, 122, 130, 134, 146, 154, 170, 172, 186, 202, \ldots$
{{OEIS|A005278}}
\end{definition}