Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

What is the next number in the following set ?

$$1,11,21,1211,111221, \ldots$$

share|improve this question

closed as primarily opinion-based by Daniel Rust, Yiorgos S. Smyrlis, egreg, Nicholas R. Peterson, vonbrand Mar 17 at 22:45

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

    
    
42 –  vonbrand Mar 17 at 22:45

3 Answers 3

up vote 5 down vote accepted

The next number is 312211. Hint read the sequence out loud!;)

share|improve this answer

See the Look-and-Say Sequence.

share|improve this answer

$312211$. And since we need $30$ characters...

share|improve this answer

Not the answer you're looking for? Browse other questions tagged or ask your own question.