#include <bits/stdc++.h>

#define ll long long
#define ld long double
#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b

using namespace std;


void calc(int n, int k,bool p,int a,int now,vector<int>& A){
    int b = 0;
    if (p){
        if (now <= k){
            rep(i,4,7){
                b = a + i;
                if (now == n){
                    A[b] ++;
                    A[b] ++;
                }else{
                    calc(n,k,p,b,now+1,A);
                    calc(n,k,p,b,now+1,A);
                }
            }
        }else{
            rep(i,1,7){
                b = a + i;
                if (now == n){
                    A[b] ++;
                }else{
                    calc(n,k,p,b,now+1,A);
                }
            }
        }
    }else{
        rep(i,1,7){
            b = a + i;
            if (now == n){
                A[b] ++;
            }else{
                calc(n,k,p,b,now+1,A);
            }
        }
    }
}

int main(){
    cout << fixed << setprecision(15);
    int N,K;cin>>N>>K;
    vector<int> A(6*N+1,0);
    vector<int> B(6*N+1,0);

    calc(N,K,true,0,1,A);
    calc(N,K,false,0,1,B);

    ll ok = 0;
    ll all = pow(6,N)*pow(6,N);

    rep(i,1,6*N+1){
        //cout << A[i] << " " << B[i] << endl;
        rep(j,1,i){
            ok += A[i]*B[j];
        }
    }
    //print(ok);
    print((long double)ok/all);



    //system("pause");
    return 0;
}