Task: Question Answering
Input (English): Question: n a series of numbers , the next number is formed by adding 1 to the sum of the previous numbers, and the 10th number is 1280. Then what is the first number in the series? (series will be like this x , x+1, (x+(x+1))+1,....... )

 Option A: 2

 Option B: 4

 Option C: 5

 Option D: 7

 Option E: 9
Output (English): Option B