Gizmodo Monday Puzzle: The Only Number That Describes Itself

Here’s a classic brainteaser that I don’t like. What’s the next number in this sequence: 1, 11, 21, 1211, 111221, …? The answer is 312211, because each number describes the digits in the number that precedes it. We open with 1, an arbitrary choice, but the next number describes 1 as “a single one,” i.e. “one one,”…

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