20,5,4,2,0
18,9,3,2,0
15,10,3,2,0
12,6,4,2,0

 1 #include <iostream>
 2 using namespace std;
 3 int main()
 4 {
 5     for(int i=20;i>=1;i--){
 6         int z=0,m=1;    //累加1/i
 7         z=z*i+m*1;
 8         m=m*i;
 9         if(z>=m) continue;
10         for(int a1=i-1;a1>=1;a1--){
11             int z1=z*a1+m*1;    //累加1/a1
12             int m1=m*a1;
13             if(z1>=m1) continue;
14             for(int a2=a1-1;a2>=1;a2--){                    
15                 int z2=z1*a2+m1*1;    //累加1/a2
16                 int m2=m1*a2;
17                 if(z2>=m2) continue;
18                 for(int a3=a2-1;a3>=1;a3--){                        
19                     int z3=z2*a3+m2*1;    //累加1/a3
20                     int m3=m2*a3;
21                     if(z3==m3)        //累加和等于1，输出结果
22                         cout<<i<<','<<a1<<','<<a2<<','<<a3<<','<<'0'<<endl;
23                 }
24             }
25         }
26     }
27     return 0;
28 }