Here’s something to investigate:
Look at the triangle using the divisors 3, 5, and 7.
Do you see a pattern? What do 3, 5, and 7 have in common?
Now try 9. Does the pattern continue?
Can you figure out what it is about 3, 5, and 7 that causes this pattern, and why it doesn’t continue at 9?
Does it continue with other numbers larger than 9?