Problem B. Boring Sum
时间限制 1000 ms
内存限制 128 MB
Number theory is interesting, while this problem is boring.
Here is the problem. Given an integer sequence a
1, a
2, …, a
n, let S(i) = {j|1<=j<i, and a
j is a multiple of a
i}. If S(i) is not empty, let f(i) be the maximum integer in S(i); otherwise, f(i) = i. Now we define bi as a
f(i). Similarly, let T(i) = {j|i<j<=n, and a
j is a multiple of a
i}. If T(i) is not empty, let g(i) be the minimum integer in T(i); otherwise, g(i) = i. Now we define c
i as a
g(i). The boring sum of this sequence is defined as b
1 * c
1 + b
2 * c
2 + … + b
n * c
n.
Given an integer sequence, your task is to calculate its boring sum.
输入数据
输出数据
Output the answer in a line.
样例输入
样例输出
样例说明
In the sample, b1=1, c1=4, b2=4, c2=4, b3=4, c3=2, b4=3, c4=9, b5=9, c5=9, so b1 * c1 + b2 * c2 + … + b5 * c5 = 136.
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