what come next 2, 7, 26, 101, 400, ?

Question

what comes next 2, 7, 26, 101, 400, ?

 

Answer 1

1595, 6374, 25489

 

4 x previous value - n

 

n = place in sequence

 

x       n  result

2       1     7

7       2     26

26     3    101

101   4    400

400   5    1595

 

If anyone can express this mathematically that would be great.