\[4n+1\quad\vdots\quad n+2\quad\to\quad 4n+8+3\quad\vdots\quad n+2\]
\[\quad \to\quad 4(n+2)+3\quad\vdots\quad n+2\]
\[n∈Z\quad\to\quad 4(n+2)\quad\vdots\quad n+2\]
\[\to\quad 3\quad\vdots\quad n+2\]
\[\to \quad n+2\quad∈\quad U_{\{3\}} = \{ ±1;±3\}\]
\[\to n\in \{-1;-3;1;-5\}\]