A :: Arithmetic Sequence
Time Limit: 3 Seconds Memory Limit: 32768 KB
Incremental Arithmetic Sequence is a sequence of integers such that the difference between the consecutive terms is constant and positive (e.g. the sequence 5, 7, 9, 11, 13, 15 with common difference of 2). You need to count the number of arithmetic sequences in the set N = {1, 2, …, n}.
Input
Each test case is represented by a line containing a positive integer n less than 1,000,001.
Output
For each n, print the number of arithmetic sequences with at least two elements mod 109+7.
Sample Input
2 3 4 1000
Sample Output
1 4 9 3281346Submit
Source: 12th Iran Nationwide Internet Contest IV