#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

struct combi{
	deque<mint> kaijou;
	deque<mint> kaijou_;
	
	combi(int n){
		kaijou.push_back(1);
		for(int i=1;i<=n;i++){
			kaijou.push_back(kaijou[i-1]*i);
		}
		
		mint b=kaijou[n].inv();
		
		kaijou_.push_front(b);
		for(int i=1;i<=n;i++){
			int k=n+1-i;
			kaijou_.push_front(kaijou_[0]*k);
		}
	}
	
	mint combination(int n,int r){
		if(r>n)return 0;
		mint a = kaijou[n]*kaijou_[r];
		a *= kaijou_[n-r];
		return a;
	}
	
	mint junretsu(int a,int b){
		mint x = kaijou_[a]*kaijou_[b];
		x *= kaijou[a+b];
		return x;
	}
	
	mint catalan(int n){
		return combination(2*n,n)/(n+1);
	}
	
};
 
int main(){
	
	int N,M;
	cin>>N>>M;
	
	combi C(5000000);
	
	vector<mint> calc(N+5,0);
	rep(i,N+5){
		calc[i] = C.combination(N,i);
		if(i!=0)calc[i] += calc[i-1];
	}
	
	mint ans = 0;
	mint t = 0;
	for(int i=M;i<=N;i++){
		t = C.combination(N,i);
		t *= i;
		ans += t;
		//mint temp = calc[N]-calc[i];
		//cout<<ans.val()<<',';
		if(N-i > i){
			ans += C.combination(N,i) * abs(N-i - i);
		}
		//cout<<ans.val()<<',';
		ans += calc[N] - calc[max(i,N-i)];
		//cout<<ans.val()<<endl;
	}
	ans *= 2;
	
	cout<<ans.val()<<endl;

	
	return 0;
}