Write a program to print the following output: [3] 5 5 5 5 5 4 4 4 4 3 3 3 2 2 1

Sure, here is a Python program that will print the desired output:

# Initialize the starting number
start = 5

# Use a for loop to iterate from the starting number down to 1
for i in range(start, 0, -1):
    # Print the current number i times
    for j in range(i):
        print(i, end=' ')
    # Print a newline
    print()

This program starts with the number 5 and uses a for loop to iterate down to 1. For each iteration, it prints the current number (i) as many times as the number itself, followed by a space. The end=' ' argument in the print function is used to separate the numbers with a space instead of a newline. After printing the current number i times, a newline is printed using the print() statement without any arguments.