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问题 1573 --拆分自然数(二)

1573: 拆分自然数(二)

时间限制: 1 Sec  内存限制: 128 MB
提交: 2  解决: 1
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题目描述

"Well, it seems the first problem is too easy. I will let you know how foolish you are later." zj says.
"The second problem is, given an positive integer N, we define an equation like this:
  N=a[1]+a[2]+a[3]+...+a[m];
  a[i]>0,1<=m<=N;
My question is how many different equations you can find for a given N.
For example, assume N is 4, we can find:
  4 = 4;
  4 = 3 + 1;
  4 = 2 + 2;
  4 = 2 + 1 + 1;
  4 = 1 + 1 + 1 + 1;
so the result is 5 when N is 4. Note that "4 = 3 + 1" and "4 = 1 + 3" is the same in this problem. Now, you do it!"
 

输入描述

The input contains several test cases. Each test case contains a positive integer N(1<=N<=120) which is mentioned above. The input is terminated by the end of file.

输出描述

For each test case, you have to output a line contains an integer P which indicate the different equations you have found.

样例输入

4
10
20

样例输出

5
42
627

来源

zj 

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