Determine all possible positive integer values of n that satisfy this equation:

Σ

j=n j=1

(x+j-1) (x+j) = 10*n

whenever x is an integer.

Note: For a desired value of n, the above equation holds true for at least one value of x.

(In reply to Possible solution by broll)

As I said in my initial comment it was early days when I encountered such a structure.  I am looking for guidance.

Please advise how I failed.

My basic logic was to treat each line of the equation for an independent value of "j" up to "n" and create a sum of those left side values and so equate to the terminal 10^n.

In my current spreadsheet I cannot reconcile such values as you have deduced.

Posted by brianjn on 2011-02-23 07:31:29