题目描述
Problem Background
jjh loves lattices.
Problem Description
jjh has a square lattice with the bottom-left corner at $(1,1)$ and the top-right corner at $(n,n)$.
jjh also has a line described by the equation $y = kx$, where $k \in (0, \infty)$.
For any given $k$, let the line pass through $cnt$ points in the lattice. jjh has a fondness level for this line, which is $cnt^2$.
jjh wants to know the sum of the fondness levels for all possible lines modulo $10^9 + 7$. Please help jjh find this result.
Input Format
A single line containing an integer $n$.
Output Format
Output a single integer, representing the sum of the fondness levels modulo $10^9 + 7$.
Sample Input and Output
Sample Input #1
2
Sample Output #1
6
Sample Input #2
1919810
Sample Output #2
107114211
Notes
Sample Explanation #1
When $k$ is $\frac{1}{2}$, the line passes through the point $(2,1)$ in the lattice, and the fondness level is $1^2 = 1$. When $k$ is $1$, the line passes through the points $(1,1)$ and $(2,2)$, and the fondness level is $2^2 = 4$. When $k$ is $2$, the line passes through the point $(1,2)$, and the fondness level is $1^2 = 1$. The sum of the fondness levels is $1 + 4 + 1 = 6$.
Data Range
This problem uses subtask testing.
| Subtask Number | $n \le$ | Score |
|---|---|---|
| 1 | 8 | 5 |
| 2 | $10^3$ | 15 |
| 3 | $10^6$ | 30 |
| 4 | $2^{31} - 1$ | 50 |
For $100\%$ of the data, $1 \le n \le 2^{31} - 1$.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分