Find the sum to `n` terms of the sequence given by `a_n=sum2^n,n in Ndot`

Explanation

Let `S_n​=sum a_n​`

`=a_1​+a_2​+....+a_n`​

`=(2^1+2^2+2^3+...+2^n)`

`=(2(2^n−1​))/(2-1)`

`=2(2^n−1)`