I want to make an item that has a variable that increases every time in a crafting table

I want to make an item, called a Weaponised Snowball that has a variable set to 1 when it is first crafted but when it is crafted like this:

/,O,/

O,X,O

/,O,/

/ means empty space

O means Snowball

X means Weaponised Snowball

In the end, it makes a Weaponised Snowball but with 4 more snowballs in it. You do it again, 9, then 13, 17...

Can you help me?