In the following number series a wrong number is given. Find out the wrong number.

1, 3, 10, 21, 64, 129, 356, 777

A. 129

B. 21

C. 10

D. 356

Answer: Option D

Solution(By Examveda Team)

The given pattern is,
2^nd term → 1*2+1 = 3
3^rd term → 3*3+1 = 10
4^th term → 10*2+1 = 21
5^th term → 21*3+1 = 64
6^th term → 64*2+1 = 129
7^th term → 129*3+1= 388
So, 7^th term 356 is wrong and must be replaced by 388.