#include <iostream>
#include <string>
#include <algorithm>
#include <cstdio>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <numeric>
#include <cmath>

using namespace std;

typedef long long int ll;
typedef pair<int,int> P;

#define all(x) x.begin(),x.end()

const ll mod = 1e9+7;
const ll INF = 1e9;
const ll MAXN = 1e9;

int main()
{
	ll n,k;
	cin>>n>>k;
	ll not_select = 0;
	if(k<n){
		not_select = n*(n+1)/2;
		for(ll i = n-1-k+1; i <= n-1; i++){
			not_select *= i;
			not_select %= mod;
		}
	}
	ll select = 0;
	if(1<k){
		select = n*(n-1)/2;
		for(ll i = n-k+1; i <= n-2; i++){
			select *= i;
			select %= mod;
		}
		select *= k*(k-1)/2;
		select %= mod;
	}

	cout << (not_select + select)%mod << endl;

	return 0;
}