https://www.codewars.com/kata/57a083a57cb1f31db7000028
Complete the function that takes a non-negative integer n as input, and returns a list of all the powers of 2 with the exponent ranging from 0 to n ( inclusive ).
Examples
n = 0 ==> [1] # [2^0]
n = 1 ==> [1, 2] # [2^0, 2^1]
n = 2 ==> [1, 2, 4] # [2^0, 2^1, 2^2]