给定一个包含 $n$ 个整数的序列 $a_1, a_2, \dots, a_n$。你需要确定满足以下条件的有序对 $(i, j)$ 的数量：$i, j \in \{1, \dots, n\}$，$i \neq j$，且 $a_i$ 是 $a_j$ 的约数。
第一行包含一个整数 $n$ ($1 \le n \le 2\,000\,000$)。第二行包含一个长度为 $n$ 的整数序列 $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 2\,000\,000$)。
输出仅一行，包含一个整数，表示所求的有序对数量。
5 2 4 5 2 6
6
有 6 对满足条件的有序对：$(1, 2), (1, 4), (1, 5), (4, 1), (4, 2), (4, 5)$。
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