Several example codes

Program Overview

This Python program reads an integer n from the user and calculates the harmonic series up to n:
\[ H_n = \frac{1}{1} + \frac{1}{2} + \frac{1}{3} + \cdots + \frac{1}{n} \]
The result is displayed with floating-point precision.

Python Code:

# Read input from user
n = int(input("Enter a positive integer n: "))

# Validate input
if n <= 0:
    print("Error: n must be a positive integer.")
else:
    # Calculate harmonic sum
    harmonic_sum = 0.0
    for i in range(1, n + 1):
        harmonic_sum += 1 / i

    # Display result
    print("\n--- Result ---")
    print(f"Harmonic sum up to {n} = {harmonic_sum:.6f}")

Sample Output:

Enter a positive integer n: 5  

--- Result ---
Harmonic sum up to 5 = 2.283334

Step-by-Step Explanation:

- The user inputs a positive integer n
- The program loops from 1 to n and adds 1/i to the total
- The result is printed with six decimal places for clarity
- This series grows slowly and is useful in math and computer science