n, k = map(int, input().split())
MOD = 10**9 + 7
kaijo_table = [1]*(n+1)
for i in range(0,n):
    kaijo_table[i+1] = kaijo_table[i] * (n-i)
ave = (n*(n+1)) // n
total = ave * kaijo_table[k] * n

flag = True
for i in range(1,k+1)[::-1]:
    if flag:
        total -= kaijo_table[i] * ave * i
        flag = False
    else:
        total += kaijo_table[i] * ave * i
        flag = True
print((total//2)%MOD)