Please help with an Excel sequence problem.

1. In Generation (1), we start off with one pair of rabbits.
2. In Generation (2), this pair of rabbits matures.
3. In Generation (3), the original pair of rabbits give birth to another pair of rabbits.
4. In Generation (4), the original pair gives birth to their second pair, and the first offspring of the original pair also matures.
5. Rabbits become infertile after 3 generations.
6. At what generation does the number of rabbit pairs reach 100,000?

Please provide the generation and population number, along with the formula. Many thanks for your help!