# General rule of sequence $1,11,21,1211,...$

I understand that a term is the same as the "reading" of the previous one. The second term is equal to 1 amount of 1 in the first term = 11. The third term is equal to amount of 1 in the second term 1 = 21.
Is there any way to deduce a general rule?

• Do you mean you want a formula for the nth term? Oct 26, 2020 at 19:13
• This sequence is pretty famous, actually. Oct 26, 2020 at 19:14
• I think this problem is still unsolved Oct 26, 2020 at 19:19
• The late, great John Conway gave an asymptotic in terms of the unique positive root of a degree 71 polynomial. Have a look. Oct 27, 2020 at 2:55
• @Integrand That's actually insane. Both Conway and Mathematics never cease to amaze me Oct 27, 2020 at 2:58