\textbf{145.} If $n \in \mathbb{N}$ and $A_n = \{m \in \mathbb{Z} \mid m > -n,\ r^m \leq 2n\}$, then the set $A_1 \cup (A_8 - A_4)$ has how many elements?
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(1) $5$ \hfill (2) $6$ \hfill (3) $7$ \hfill (4) $8$
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