#include<bits/stdc++.h>
using lint=long long;
using real=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint n,k;std::cin>>n>>k;
    lint mod=1'000'000'007;
    lint inv2=(1+mod)/2;
    lint ans=inv2*(((n-k)*(n+1)+k*(k-1)/2)%mod)%mod;
    for(lint i=n;i>n-k;i--)ans=ans*i%mod;
    std::cout<<ans<<'\n';
}