Look-and-say sequence

[Jefke2120]

Dear,
I have been looking for a mathematical proof of the Conway sequence (1,11,21,1211,111221,312211,...) that says why their is no 4 in these numbers. Or why their are only the numbers 1,2,3. Does someone know how to proof?

Thank you!

Jefke2120

 

[pka]

I have been looking for a mathematical proof of the Conway sequence (1,11,21,1211,111221,312211,...) that says why their is no 4 in these numbers. Or why their are only the numbers 1,2,3. Does someone know how to proof?

Have a look at this LINK

 

[Jefke2120]

Have a look at this LINK

I can't find a written proof.
But already thank you

 

[pka]

I can't find a written proof.

Did you explore the many links on that page?
They lead to many comments on the Conway sequence.
If you cannot find what you want on that page, then I doubt we can help you.