def f(N, A):
    v = A[0] * A[1] + A[0] + A[1]
    for i in range(2, N):
        v = v * A[i] + v + A[i]
    return v


T = int(input())
for _ in range(T):
    N = int(input())
    A = list(map(int, input().split()))
    v = f(N, A)
    print(v)