给定一个正四面体。它的每条棱都被 $n-1$ 个分点分成了 $n$ 条等长的线段。设 $M$ 为所有分点的集合。问以 $M$ 中的点为顶点的非退化四面体有多少个？
输入的第一行包含一个整数 $n$ ($2 \le n \le 4000$)。
在输出的第一行打印问题的答案。
样例
输入格式 1
2
输出格式 1
12
输入格式 2
37
输出格式 2
65561472
QOJ.ac
QOJ
Límite de tiempo: 3 s
Límite de memoria: 256 MB
Puntuación total: 100
#100. 四面体
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