Saturday, August 17, 2024

The Look and Say Sequence, A005150

The Look and Say Sequence begins 1, 11, 21, 1211, 111221, 312211...

Each term is a description of the prior term. For example, the second term, 11, is read as one 1 and describes the previous term, 1. The fifth term, 111221, is read as one 1, one 2, two 1s and describes the prior term, 1211.

The sequence is often attributed to the mathematician, John Conway. However, according to the On-Line Encyclopedia of Integer Sequences (OEIS), the sequence's first mention dates back to the 1977 International Mathematical Olympiad in Belgrave, Yugoslavia. In the OEIS, the sequence is A005150.

Recently, Scientific America wrote about the sequence in their puzzle section: https://www.scientificamerican.com/game/math-puzzle-next-sequence/


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