Look and Say Sequence
The sequence was first proposed by John Conway, who published it in 1986. The sequence goes as follows:

1
11
21
1211
111221
312211
13112221
1113213211
31131211131221

Can you spot the pattern?

It goes as follows.
1 can be read as 'one one' hence the 11 in the next term.
11 can be read as 'two ones' hence the 21.
21 can be read as 'one two, one one' hence the 1211.
The sequence continues indefinitely.

The formula to work out the nth term of the look and say sequence hasn't yet been found, and it's a complex sequence, despite being easy to understand.

By Ananth Balakrishnan and