Each week, we post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.
The sequence of numbers a1, a2, a3, …, an, … is defined by for each integer n â‰¥ 1.
The sum of the first 20 terms of this sequence
The sum of the first 19 terms of this sequence
See the answer choices and submit your pick over on our Challenge Problem page.