I need to know the next number sequence and how you got there! 1,11, 21, 1211, 111221, ___?___

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Originally Posted by Nodogs

I need to know the next number sequence and how you got there! 1,11, 21, 1211, 111221, ___?___

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I should slap you:

It would be something like 11111221 multiply by two

This is a classic sequence.

312211 is the next term:

It's a self describing sequence, A005150 in OEIS

The first term is 1, the second is 11 (one 1), the third is 21 (two 1s), the fourth is 1211 (one 2 one 1), the next is 111221 (one 1 one 2 two 1s), so the next is 312211 (three 1s two 2s one 1), etc.

Good try toryadamz :)