#include <bits/stdc++.h>
using namespace std;

#define int long long
//#define uint __int128_t

#define pb push_back
#define fi first
#define se second
#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
#define low(a,b) lower_bound(all(a),(b))
#define upp(a,b) upper_bound(all(a),(b))
#define fill(i,n) memset(i,n,sizeof(i))
#define endl '\n'
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0)
typedef long long ll;
typedef pair<int,int>pint;
typedef vector<int>vint;
typedef vector<vint> vvint;
typedef vector<pint>vpint;
typedef pair<pint,int> P1;
typedef pair<int,pint> P2;
typedef pair<pint,pint> PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD=1000000007;
const ll INF=1e18;

int N,K;
double dp1[100010];
double dp2[100010];


signed main() {
    IOS();
    //(1ll<<N)シフト演算のオーバーフローに気をつける
    cin>>N>>K;
    dp1[0]=dp2[0]=1;
    rep(i,1,N+1){
        rrep(j,0,91){
            rep(k,1,7){
                dp1[j+k]+=dp1[j]/6;
            }
            if(i<=K){
                rep(k,4,7){
                    dp2[j+k]+=dp2[j]/3;
                }
            }else{
                rep(k,1,7){
                    dp2[j+k]+=dp2[j]/6;
                }
            }
            dp1[j]=dp2[j]=0;
        }
    }

    double ans=0;
    rep(i,0,111){
        rep(j,i+1,111){
            ans+=dp1[i]*dp2[j];
        }
    }
    cout<<ans<<endl;
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    




















































    return 0;
}