SIZE=10**5+1; MOD=10**9+7 #998244353 #ここを変更する

inv = [0]*SIZE  # inv[j] = j^{-1} mod MOD
fac = [0]*SIZE  # fac[j] = j! mod MOD
finv = [0]*SIZE # finv[j] = (j!)^{-1} mod MOD
fac[0] = fac[1] = 1
finv[0] = finv[1] = 1
for i in range(2,SIZE):
    fac[i] = fac[i-1]*i%MOD
finv[-1] = pow(fac[-1],MOD-2,MOD)
for i in range(SIZE-1,0,-1):
    finv[i-1] = finv[i]*i%MOD
    inv[i] = finv[i]*fac[i-1]%MOD

def Lagrange_interpolation(a,t):
    n = len(a)-1
    t %= MOD
    if 0 <= t <= n: return a[t]
    rprod = [1]*(n+2)
    r = 1
    for i in range(n+2):
        rprod[n+1-i] = r
        r = r*(t-n+i)%MOD
    ans, lprod = 0, 1
    for i,ai in enumerate(a):
        bunsi = lprod*rprod[i+1]%MOD
        bunbo = finv[i]*finv[n-i]%MOD*(-1 if (n-i)%2 else 1)
        ans += bunsi*bunbo%MOD*ai%MOD
        lprod = lprod*(t-i)%MOD
    return ans%MOD

n,k = map(int,input().split())
a = [pow(i,k,MOD) for i in range(2*k+4)]
for i in range(1,2*k+4): a[i] += a[i-1]
print(Lagrange_interpolation(a,n)%MOD)