A363054 Look and say sequence: describe the previous term (method A, starting with 20).

20, 1210, 11121110, 31123110, 132112132110, 11131221121113122110, 311311222112311311222110, 1321132132211213211321322110, 11131221131211132221121113122113121113222110, 3113112221131112311332211231131122211311123113322110

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..21

Julia Witte Zimmerman, Denis Hudon, Kathryn Cramer, Alejandro J. Ruiz, Calla Beauregard, Ashley Fehr, Mikaela Irene Fudolig, Bradford Demarest, Yoshi Meke Bird, Milo Z. Trujillo, Christopher M. Danforth, and Peter Sheridan Dodds, Tokens, the oft-overlooked appetizer: Large language models, the distributional hypothesis, and meaning, arXiv:2412.10924 [cs.CL], 2024. See pp. 21, 28.

Example

The term after 1210 is given by saying "I see one 1, one 2, one 1, and one 0", and then writing down the digits as 11-12-11-10, yielding 11121110.

Mathematica

NestList[FromDigits@ Flatten@ Map[Reverse@ Tally[#][[1]] &, Split@ IntegerDigits[#] ] &, 20, 12] (* Michael De Vlieger, Jul 05 2023 *)

Prog

(Python)
from itertools import count, groupby, islice
def LS(n): return int(''.join(str(len(list(g)))+k for k, g in groupby(str(n))))
def agen(an=20): yield an; yield from (an:=LS(an) for n in count(1))
print(list(islice(agen(), 10))) # Michael S. Branicky, May 15 2023

Crossrefs

Other look-and-say sequences: A005150, A001155, A006751, A006715, A001140, A001141, A001143, A001145, A001151, A007651, A001387, A098595, A045918.

Sequence in context: A203775 A184269 A042745 * A158912 A036067 A294191

Adjacent sequences: A363051 A363052 A363053 * A363055 A363056 A363057

Keyword

nonn,base

Author

Julia Zimmerman, May 15 2023

Status

approved