import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

class Combination(object):
	def __init__(self, N, con):
		self.fac = [0] * (N + 1)
		self.inv = [0] * (N + 1)
		self.finv = [0] * (N + 1)
		self.fac[0], self.fac[1] = 1, 1
		self.inv[1] = 1
		self.finv[0], self.finv[1] = 1, 1

		# 前計算
		for i in range(2, N + 1):
			self.fac[i] = self.fac[i - 1] * i % con
			self.inv[i] = self.inv[con % i] * (con - (con // i)) % con
			self.finv[i] = self.finv[i - 1] * self.inv[i] % con

	def com(self, N, k):
		return (self.fac[N] * self.finv[k] * self.finv[N - k]) % con

#処理内容
def main():
	N, K = getlist()
	ans = 0
	C = Combination(N, con)
	if K == 1:
		ans = int((N + 1) * (N - 1) * N // 2)
		print(ans)
		return

	for i in range(1, N):
		ans += i * int(K * (K - 1) // 2) * C.fac[N - 2] * C.finv[N - K]
		ans += i * C.fac[N - 1] * C.finv[N - 1 - K]

	ans += N * C.fac[N - 1] * C.finv[N - 1 - K]

	print(ans % con)

if __name__ == '__main__':
	main()