In this post, We will see how to write a python program for finding Sum of cubes of first n natural numbers in different ways.

Example:

Input: N = 2
Output: 1 * 1 * 1 + 2 * 2 *2 => 9 OR 
13 + 2 3 => 9

Input: N = 3
Output: 1 * 1 * 1 + 2 * 2 * 2 + 3 * 3 * 3 => 36 OR
13 + 2 3 + 3 3 => 36

Now, Let’s see the codes:
Code 1: Run a loop from 2 to N and for each i, find i ³ and adding to the sum.

# code: 1

# first 5 natural numbers
N = 5

# initialize variable with 1
sumCube = 1

# loop from 2 to N
for i in range(2, N + 1) :
    
    # cube summation
    sumCube += i ** 3
    
# print the result
print("Sum of Cubes of first", N ,
      "Natural Numbers:",sumCube)

Output:

Sum of Cubes of first 5 Natural Numbers: 225.0

Code 2: Create user defined function, main and then apply the previous code logic.

# code: 2

# Define a user defined 
# function for finding
# sum of cubes of 1st
# N natural Numbers
def sumOfCubes(Num) :

    # initialize variable with 1
    sumCube = 1

    # loop from 2 to N
    for i in range(2, Num + 1) :

        # Cube summation
        sumCube += i ** 3
        
    # return result
    return sumCube

# main code
if __name__ == "__main__" :

    # first 5 natural numbers
    Num = 5
    
    # function calling and
    # printing the result
    print("Sum of Cubes of first", Num ,
          "Natural Numbers:",
          sumOfCubes(Num))

Output:

Sum of Cubes of first 5 Natural Numbers: 225.0

Code 3: Run a loop from 2 to N and for each i, find i * i * i and adding to the sum.

# code: 3

# Define a user defined 
# function for finding
# sum of cubes of 1st
# N natural Numbers
def sumOfCubes(Num) :

    # initialize variable with 1
    sumCube = 1

    # loop from 2 to N
    for i in range(2, Num + 1) :

        # Cube summation
        sumCube += i * i * i
        
    # return result
    return sumCube

# main code
if __name__ == "__main__" :

    # first 5 natural numbers
    Num = 5
    
    # function calling and
    # printing the result
    print("Sum of Cubes of first", Num ,
          "Natural Numbers:",
          sumOfCubes(Num))

Output:

Sum of Cubes of first 5 Natural Numbers: 225.0

Code 4: By Using given formula :

sum of the cubes of 1st N Natural numbers:
 ((N) * (N + 1) / 2 ) 2 

# code: 4

# Define a user defined 
# function for finding
# sum of cubes of 1st
# N natural Numbers
def sumOfCubes(Num) :
    
    # return result
    return ((Num) * (Num + 1) / 2 ) ** 2
    
# main code
if __name__ == "__main__" :

    # first 5 natural numbers
    Num = 5
    
    # function calling and
    # printing the result
    print("Sum of Cubes of first", Num ,
          "Natural Numbers:",
          sumOfCubes(Num))

Output:

Sum of Cubes of first 5 Natural Numbers: 225.0

Code 5: By making a anonymous function.

# code: 5

# Define a annonymous
# function for returning
# sum of cubes of 1st
# N natural Numbers
sumOfCubes = lambda Num : ((Num) * (Num + 1) / 2 ) ** 2
    
# main code
if __name__ == "__main__" :

    # first 5 natural numbers
    Num = 5
    
    # function calling and
    # printing the result
    print("Sum of Cubes of first", Num ,
          "Natural Numbers:",
          sumOfCubes(Num))

Output:

Sum of Cubes of first 5 Natural Numbers: 225.0