Look and Say Sequence Steps

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram CDF Player or other Wolfram Language products.

Requires a Wolfram Notebook System

Edit on desktop, mobile and cloud with any Wolfram Language product.

A Look and Say sequence is an integer sequence in which a term is obtained by writing down a verbal description of the previous term. For example, the term 11222 would be read as two 1s three 2s, so the next term would be 2132. Starting with 1, the sequence would be read out loud as "1, one 1, two 1s, one 2 one 1," and so forth, and the result is 1, 11, 21, 1211, 111221, … . The visualization checks whether the initial string could be the result of an earlier step and computes the next step. The buttons at the bottom say the descriptions out loud.

Contributed by: Michael Schreiber (March 2011)
Open content licensed under CC BY-NC-SA



Conway called the recursion "audioactive decay" and proposed to rename substrings like atoms because of their matching relative abundance in sequence terms derived from random initial strings.

Feedback (field required)
Email (field required) Name
Occupation Organization
Note: Your message & contact information may be shared with the author of any specific Demonstration for which you give feedback.