Question 495959
the formula that works with the data is as follows:


a[n] = a[n-1] + (n-1)^2


here's a table of values based on that formula.
the table starts with a[1] being given as 0.


<pre>
        n        (n-1)^2         a[n]

        1        n/a            given as 0
        2        1^2 = 1        1 + 0 = 1
        3        2^2 = 4        4 + 1 = 5
        4        3^2 = 9        9 + 5 = 14
        5        4^2 = 16       16 + 14 = 30
        6        5^2 = 25       25 + 30 = 55
        ...
</pre>


you are given that the a[1] = 0
the rest of them are derived from the formula.
the same formula is used every time.
let me know if this solves the problem for you.