The &nbsp; [[wp:Look and say sequence|Look and say sequence]] &nbsp; is a recursively defined sequence of numbers studied most notably by &nbsp; [[wp:John Horton Conway|John Conway]].


The  &nbsp; '''look-and-say sequence''' &nbsp; is also known as the &nbsp; '''Morris Number Sequence''', &nbsp; after cryptographer Robert Morris, &nbsp; and the puzzle  &nbsp; ''What is the next number in the sequence 1, &nbsp; 11, &nbsp; 21, &nbsp; 1211, &nbsp; 111221?'' &nbsp; is sometimes referred to as the ''Cuckoo's Egg'', &nbsp; from a description of Morris in Clifford Stoll's book &nbsp; ''The Cuckoo's Egg''.


'''Sequence Definition'''
* Take a decimal number
* ''Look'' at the number, visually grouping consecutive runs of the same digit.
* ''Say'' the number, from left to right, group by group; as how many of that digit there are - followed by the digit grouped.
: This becomes the next number of the sequence.


'''An example:''' 
* Starting with the number 1, &nbsp; you have ''one'' 1 which produces 11
* Starting with 11, &nbsp; you have ''two'' 1's. &nbsp; I.E.: &nbsp; 21
* Starting with 21, &nbsp; you have ''one'' 2, then ''one'' 1. &nbsp; I.E.: &nbsp; (12)(11) which becomes 1211
* Starting with 1211, &nbsp; you have ''one'' 1, ''one'' 2, then ''two'' 1's. &nbsp; I.E.: &nbsp; (11)(12)(21) which becomes 111221


;Task:
Write a program to generate successive members of the look-and-say sequence.


;Related tasks:
* &nbsp; [[Fours is the number of letters in the ...]]
* &nbsp; [[Number names]]
* &nbsp; [[Self-describing numbers]]
* &nbsp; [[Self-referential sequence]]
* &nbsp; [[Spelling of ordinal numbers]]


;See also:
* &nbsp; [https://www.youtube.com/watch?v=ea7lJkEhytA Look-and-Say Numbers (feat John Conway)], A Numberphile Video.
* &nbsp; This task is related to, and an application of, the [[Run-length encoding]] task.
* &nbsp; Sequence [https://oeis.org/A005150 A005150] on  The On-Line Encyclopedia of Integer Sequences.
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