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Encyclopedia > Look and Say sequence

Description

In mathematics, the Look and Say sequence is the sequence of integers beginning as follows:


1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, ...


To generate a member of the sequence from the previous member, read off the digits of the previous member, counting the number of digits in groups of the same digit. This idea is clarified by several examples.


1 is read off as "one 1" that is, 11.


11 is read off as "two 1's" that is, 21.


21 is read off as "one 2, then one 1" that is, 1211.


1211 is read off as "one 1, then one 2, then two 1's" that is, 111221.


The idea is similar to that of run-length encoding.


External links

  • On-Line Encyclopedia of Integer Sequences (http://www.research.att.com/cgi-bin/access.cgi/as/njas/sequences/eisA.cgi?Anum=A005150)
  • MathWorld (http://mathworld.wolfram.com/LookandSaySequence.html)

  Results from FactBites:
 
Look-and-say sequence - Wikipedia, the free encyclopedia (305 words)
In mathematics, the look-and-say sequence is the sequence of integers beginning as follows:
To generate a member of the sequence from the previous member, read off the digits of the previous member, counting the number of digits in groups of the same digit.
be the length of the sequence on the ith iteration.
  More results at FactBites »


 

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