Collatz Conjecture Visualizer

Take any positive integer: if even, halve it; if odd, triple it and add 1. Repeat. The conjecture (unproven since 1937) says every number eventually reaches 1. Explore sequence lengths, stopping times, and the tree structure.

Sequence

Stopping Times

Tree

Starting number

Range for stopping times 1 – 500

Tree depth 6

Enter a number and press Trace.

Famous sequences:
27 → 111 steps, peak 9232
871 → 178 steps
6171 → 261 steps
77031 → 350 steps
837799 → 524 steps (record to 1M)

Open problem: Proved computationally up to 2^68 ≈ 2.95×10²⁰ (Oliveira e Silva, 2010). Erdős: "Mathematics is not yet ready for such problems." Terras (1976) showed almost all integers have stopping time (time to reach a value less than itself). The sequence is encoded in OEIS as A006577 (stopping times).