#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
const int INF = 1e9;
const int MOD = 1000000007;


const int MAX = 1000000;
long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

//順列を計算
long long PER(int n,int k){
        if(n < k) return 0;
        if(n < 0 || k < 0) return 0;
        return (fac[n] * finv[n-k]) % MOD;
}

long long modpow(long long a, long long b,long long mod){
        bitset<40> bit(b);
        string s = bit.to_string();
        long long ret = 1;
        for (int i = 0;i< s.length(); ++i){
                ret = (ret * ret) % mod;
                if(s[i]-'0') ret = (ret * a) % mod;
        }
        return ret;
}

long long inverse(long long x,long long mod){
    return modpow(x,mod-2,mod);
}

int main(){
    COMinit();
    ll n,k;
    cin >> n >> k;
    if(k==1){
        cout << ((n+1)*n*(n-1))/2 << endl;
        return 0;
    }
    ll ans = 0;
    ll res = (PER(n-1,k) + ((COM(n-2,k-2) * fac[k])%MOD * inv[2])%MOD)%MOD;
    for(ll i=1;i<n;i++){
        ans = (ans + (res * i)%MOD)%MOD;
    }
    ans = (ans + (n * PER(n-1,k))%MOD)%MOD;
    cout << ans << endl;
    return 0;
}