Design a COBOL program that prompts the user to enter a positive integer and outputs the Collatz sequence of that number. The program should validate user input to ensure that the entered number is a positive integer. The Collatz sequence should start with the entered number and follow the rules of the Collatz conjecture until it reaches the number 1. The program should output each number in the sequence on a separate line. The program should include meaningful comments and be written in a clear and concise style.
This prompt doesn't seem malicious.