Rules
There is one sequence below. It follows a rule. You have three attempts to name the rule. Nothing is stored, nothing is sent — the checker runs in your browser.
Sequence
1 · 11 · 21 · 1211 · 111221 · ?
Attempts left: 3
Why
Most puzzles reward speed. This one rewards noticing. The sequence is old and famous; if you already know it, enjoy the silence.
- No account, no cookies, no tracking.
- Works offline once loaded.
- Source is a single script — read it if you like.