Apply the 3n+1 rule: if n is even, divide by 2; if n is odd, triple and add 1. Every tested number eventually reaches 1 — but it's still an unproven conjecture. BigInt support lets you test gigantic starting values.
These are record-holders: each sets a new stopping-time record starting from 1.
Y-axis is log-scaled to show the characteristic hailstone pattern.