number problem!!

[southportram]

this one got given to us at school years ago and i just wondered if anyone else knew it!!

What is the next line of numbers??

1

11

21

1211

111221

312211

13112221

1113213211

??????????????

[gen2]

31131211131221

[BabsG]

Why???

[smouse]

you say what you see

so from 1113213211

there are 3 ones 1 three 1 two etc

[gen2]

The first line is made up of one 1 (1 1)
The second line is made up of two 1's (2 1)
The next line is made up of one 2 and one 1 (1 2 1 1)
The next line is made up of one 1, one 2 and two 1's (1 1 1 2 2 1)

and so on . . .

[wideboy]

Never seen this before - very clever. An interesting 'twist' on Pascal's Triangle?