Sunday 31 May 2015

algebra precalculus - Sum of series: $1*3*(2^2) + 2*4*(3^2) + 3*5*(4^2) + dots$?

I am trying to find the sum of the above series.



The sum till n terms can be found using power series expansion. However, I'm trying to solve this using the method of difference (a.k.a. Telescoping sum or $V_n$ method).



In this method, the general term is expressed as the difference between two consecutive values of some function. Like the following:




$T_n = V_n - V_{n-1}$



and then the sum is taken which comes to be



$S_n = V_n - V_0$



The general term of the series in question can be represented as a product:



$T_n = n(n+1)^2(n+2)$




But I am unable to represent this as a difference. How can I proceed from here to find the sum?

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