1 // 2 //by coolxxx 3 //#include<bits/stdc++.h> 4 #include<iostream> 5 #include<algorithm> 6 #include<string> 7 #include<iomanip> 8 #include<map> 9 #include<memory.h>10 #include<time.h>11 #include<stdio.h>12 #include<stdlib.h>13 #include<string.h>14 //#include<stdbool.h>15 #include<math.h>16 #define min(a,b) ((a)<(b)?(a):(b))17 #define max(a,b) ((a)>(b)?(a):(b))18 #define abs(a) ((a)>0?(a):(-(a)))19 #define lowbit(a) (a&(-a))20 #define sqr(a) ((a)*(a))21 #define swap(a,b) ((a)^=(b),(b)^=(a),(a)^=(b))22 #define mem(a,b) memset(a,b,sizeof(a))23 #define eps (1e-8)24 #define J 1025 #define mod 100000000726 #define MAX 0x7f7f7f7f27 #define PI 3.1415926535897932328 #define N 200429 using namespace std;30 typedef long long LL;31 int cas,cass;32 int n,m,lll,ans;33 double f[N][24];34 void init()35 {36     int i,j,k;37     for(i=0;i<18;i++)f[0][i]=0;38     for(i=1;i<N;i++)f[i][0]=2000000000;39     for(j=1;j<18;j++)40     {41         for(i=1;i<N;i++)42         {43             f[i][j]=2000000000;44             for(k=1;k<=i;k++)45                 f[i][j]=min(f[i][j],(f[i-k][j]*(i-k+1)+f[k-1][j-1]*k)/(i+1)+1);46         }47     }48 }49 int main()50 {51     #ifndef ONLINE_JUDGE52 //    freopen("1.txt","r",stdin);53 //    freopen("2.txt","w",stdout);54     #endif55     int i,j,k;56     init();57 //    for(scanf("%d",&cas);cas;cas--)58 //    for(scanf("%d",&cas),cass=1;cass<=cas;cass++)59 //    while(~scanf("%s",s+1))60     while(~scanf("%d",&n))61     {62         scanf("%d",&m);63         printf("%.6lf\n",f[n][min(m,17)]);64     }65     return 0;66 }67 /*68 //69 70 //71 */