An exponential backoff, measured in milliseconds, which
retries until it reaches max_retries. As an exponential
backoff, it follows the formula an^b+c, where a is
coefficient, b is exponent, c is constant, and
n is the attempt number. This means that the total time
possible to spend waiting in a retry is given by the sum,
from 1 to max_retries, of an^b+c.