In each of the following number series, the wrong number is given, find out that number.
1, 6, 21, 65, 201, 606, 1821
1
1
2
21
3
65
4
201
5
606
In each of the following number series, the wrong number is given, find out that number.
1, 6, 21, 65, 201, 606, 1821