// yukicoder 823 Many Shifts Easy
// 2019.9.11 bal4u

#include <stdio.h>

typedef long long ll;
#define MOD 1000000007
#define INV4 250000002

int main()
{
	int i, N, K, ans;
	ll a;
	
	scanf("%d%d", &N, &K);
	a = 1; for (i = N-K+1; i <= N; i++) a = a * i % MOD;
	ans = ((ll)(N+1)*(N-K)*2 + (ll)K*(K-1)) % MOD;
	ans = a * ans % MOD * INV4 % MOD;
	if (ans < 0) ans += MOD;
	printf("%d\n", ans);
	return 0;
}