November 2020 - Solution
A simple solution can be based on the ability to use power manipulations to perform subtractions:
4, 2^2, 31 4, 2^2^31 4^2^2^31 4^2, 2^(2^31-1) 4^2, 2, 2^31-1
Even without the subtraction trick, there are many other methods of solution, e.g.,
2, 2^4, 536870911, 2^3 2, 2^2147483644, 2^3 2^2^2147483644, 2^3 2^2^2147483647 2, 2^2147483647 2, 2, 2147483647
If we begin with 64, an endless stream of "2" can be generated:
64 2, 8 256 16, 2 2^16 2, 2^8 16, 2, 2
Repeating this and using a subtraction trick, one can reach 4, 2^2, 31 and proceed as before. Also, for those who love brute-force solutions, one can simply generate "2" for 2147483647 times and apply as powers on 2^2.