| (1) $4$ | (2) $5$ | (3) $6$ | (4) $7$ |
\textbf{145-} If $n \in \mathbb{N}$ and $A_n = \left\{ m \in \mathbb{Z} : |m| \leq n,\ 2^m \leq 2n \right\}$, then the set $A_1 \cup (A_6 - A_4)$ has how many elements?
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(1) $4$ & (2) $5$ & (3) $6$ & (4) $7$
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