What is the next number?

[Evan]

Apparently 4 minutes.

[Evan]

There are 3 1's, 1 3, 1 2, 1 1, 1 2, 1 2, and 2 1's

[Duke]

You wrote it in a way that will be too easy to solve. Having the numbers in a column makes it simpler to see what's happening, for some reason, and removes the tendency to think of the values as "one", "eleven", "twenty-one"... and so on.

It took me a little over an hour to get it the first time I ever saw it, and at the end I was like "GOD DAMN IT!"

~D

[jstnrgrs]

do any 4's ever apear in this sequence? I haven't found any yet.

[Evan]

No, any 4 number stretch can always be reduced.

[AZK]

Get a harder one:
31131211131221

Edit: Damn you guys are quick..