Nth term (formula) of 1² , 2² ,3² ,4² ,5²

Plot the points (0,6), (3,15.8), and (9.5,0) using the graphing tool, and find the function

Pepe and leo deposits money into their savings account at the end of the month the table shows the account balances. if there pattern of savings continue and neither earns interest nor withdraw any of the money , how will the balance compare after a very long time ?

Precalculus question, image attached.