#include <bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//#include<boost/multiprecision/cpp_dec_float.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
#define first fi
#define second se
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

//using lll=boost::multiprecision::cpp_int;
//using Double=boost::multiprecision::number<boost::multiprecision::cpp_dec_float<1024>>;//仮数部が1024桁
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

template <typename T>
T mypow(T x, T n, const T &p = -1)
{ //x^nをmodで割った余り

	if(p!=-1){
		x%=p;
	}
	T ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;


void solve()
{	
	int n,k;
	cin>>n>>k;

	double ans=0;
	vector<ll>cnt(n*6+1),cnt2(n*6+1),cnt3(n*6+1);
	vector<int>v(n),v2(n),v3(n);
	auto rec=[&](auto self,int id)->void{
		if(id==n){
			int sum=accumulate(all(v),0);
			cnt[sum]++;
			return;
		}
		for(int i=1;i<=6;++i){
			v[id]=i;
			self(self,id+1);
		}
	};

	int x[]={4,4,5,5,6,6};

	auto rec2=[&](auto self,int id)->void{
		if(id==k){
			int sum=accumulate(all(v2),0);
			cnt2[sum]++;
			return;
		}
		rep(j,6){
			int i=x[j];
			v2[id]=i;
			self(self,id+1);
		}
	};
	auto rec3=[&](auto self,int id)->void{
		if(id==n-k){
			int sum=accumulate(all(v3),0);
			cnt3[sum]++;
			return;
		}
		for(int i=1;i<=6;++i){
			v3[id]=i;
			self(self,id+1);
		}
	};
	rec(rec,0);
	rec2(rec2,0);
	rec3(rec3,0);
	for(int i=n;i<=n*6;++i){
		for(int j=n-k;j<=(n-k)*6;++j){
			for(int a=k*4;a<=6*k;++a){
				if(i<j+a){
					ans+=cnt[i]*cnt2[a]*cnt3[j];
				}
			}
		}
	}
	ans/=pow(6,n*2);
	cout<<ans<<"\n";
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}