The look and say sequence is a sequence of integerse that is defined from the previus sequence by noting how many times an integer is occuring in the prevoius sequence.

For example, [1] → [11] → [21] → [1211] → [111221] → [312211] ...

In the above example 1 is occuring one time giving [11], the next one is occuring two times giving [21] and so on.

Originaly this sequence was discovered by John Conway, also famous for the game of life.

This is an implementation of the above look and see sequence in python:

#!/usr/bin/env python def las(start,seqs): prev=[start] print prev for i in range(seqs): cnt=0 current=[0] s=prev[0] for j in range(len(prev)): if s==prev[j]: current[cnt]+=1 if(current[cnt]==1): current.append(s) else: s=prev[j] cnt=len(current) current.append(1) current.append(s) print current prev=current

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