Look and say sequence

The series given below is called the "look - and - say" sequence.

 

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

To generate a member of the sequence from the previous member, one must read  the digits of the previous member, thus:

• 1 is to be  read as "one 1" or 11.
• 11 is to be  read as "two 1s" or 21.
• 21 is to be  read as "one 2, then one 1" or 1211.
• 1211 is to be  read as "one 1, then one 2, then two 1s" or 111221.
• 111221 is to be  read as "three 1s, then two 2s, then one 1" or 312211