Originally Posted by

**grafan** My problem is that I have to solve a number of notations, and my final goal is to find the factors of $\displaystyle x $, not the result of the notation. So I always want the power only with one variable.

A lot of my notations have $\displaystyle x $ raised to the power of more variables (3 or 4) or I have more summations. I posted one of the simplest form to understand the logic.

So, any idea about the changes - and the logic - in the limits of double sum if I swap $\displaystyle m $ with $\displaystyle a+b $?