import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n,m = na()

p = 10 ** 9 + 7
N = 2*10 ** 6  # N は必要分だけ用意する
fact = [1, 1]  # fact[n] = (n! mod p)
factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
inv = [0, 1]  # factinv 計算用

for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)
def cmb(n, r):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return ((fact[n] * factinv[r])%p) * factinv[n-r] % p

def pem(n,r):
    if (r < 0) or (n < r):
        return 0
    return (fact[n] * factinv[r])%p

ans = 0
for k in range(m,n+1):
    ans+=n*cmb(n,k)%p
    ans%=p
#print(ans)
for k in range(1,n+1):
    N = min((n+k)//2,n)
    #print(cmb(n,N-k),cmb(n,m-k-1))
    ans+=k*(cmb(n,N-k)-cmb(n,m-k-1))%p
    ans%=p
    #print(ans)
for k in range(1,n+1):
    N = min(n-m,(n+k)//2)
    #print(cmb(n,N-k),cmb(n,-k-1))
    ans+=+k*(cmb(n,N-k)-cmb(n,-k-1))%p
    ans%=p
print(ans)