N = int(input())
A = list(map(int, input().split()))
MOD = 10**9 + 7

def pascal_triangle(n):
    triangle = []
    for depth in range(n):
        row = []
        for i in range(depth + 1):
            if i == 0 or i == depth:
                row.append(1)
            else:
                v = (triangle[depth-1][i-1] + triangle[depth-1][i]) % MOD
                row.append(v)
        triangle.append(row)
    return triangle[-1]


P = pascal_triangle(N)
ans = 0
for i in range(N):
    ans += (A[i] * P[i]) % MOD
    ans %= MOD
print(ans)