Imagine that someone gives you a list of five numbers: 1, 6, 21, 107 and — wait for it — 47,176,870. Can you guess what comes next? If you’re stumped, you’re not alone. These are the first five busy beaver numbers. They form a sequence that’s intimately tied to one of the most notoriously difficult questions in theoretical computer science. Determining the values of busy beaver numbers is a…Source