n,c = map(int,input().split())
a = list(map(int,input().split()))

R = [[0] * n for _ in range(n)]
for i in range(n):
    for j in range(i,n):
        R[j][i] = a[i]
#print(R)
P = 10 ** 9 + 7
def seki(x,y):
    l = [[0] * n for _ in range(n)]
    for i in range(n):
        for j in range(n):
            for k in range(n):
                l[i][j] += x[i][k] * y[k][j] % P
            l[i][j] %= P
    return l
e = [[0] * n for _ in range(n)]
for i in range(n):
    e[i][i] = 1
    u = c
while c:
    if c & 1:
        e = seki(e,R)
    R = seki(R,R)
    c >>= 1
ans = 0
for i in range(n):
    ans += e[-1][i]
    ans %= P
for i in a:
    ans -= pow(i,u,P)
    #print(pow(i,c,P))
    ans %= P
print(ans)
#print(e)