A sequence of natural numbers is written according to the following rule: the first two numbers are chosen and thereafter, in order to write a new number, the sum of the last numbers is calculated using the two written numbers, we find the greatest odd divisor of their sum and the sum of this greatest odd divisor plus one is the following written number. The first numbers are $25$ and $126$ (in that order), and the sequence has $2015$ numbers. Find the last number written.