Busy Beaver

The non-computable sequence: max steps before halting — Σ(n) grows faster than any computable function

Steps taken
0
Ones on tape
0
Current state
A
Σ(n) champion
Σ(n) = max 1s written by an n-state TM before halting. BB is uncomputable: no algorithm can compute it. BB(5) is known (47,176,870). BB(6) > 10↑↑15. BB(7) is independent of ZFC set theory.