Talk:Forest/@comment-2601:C1:8001:CB27:58E2:5FC9:C6A4:7AA2-20180414122952

You can use an online calculator for summation to get the exact number from the formula below. Wolfram alpha is good. Search for "summation" and turn index on. The formula will be as below, with the index going from zero (2^0 = 1) to monster levels required - 1.