Write a python function to find the cube sum of first n even natural numbers.
def cube_Sum(n): 
    sum = 0
    for i in range(1,n + 1): 
        sum += (2*i)*(2*i)*(2*i) 
    return sum
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a python function to find the cube sum of first n even natural numbers.
def cube_Sum(n): 
    sum = 0
    for i in range(1,n + 1): 
        sum += (2*i)*(2*i)*(2*i) 
    return sum[/INST]assert cube_Sum(2) == 72
assert cube_Sum(3) == 288
assert cube_Sum(4) == 800</s>