Homework Help: Generate a function from a list of numbers

1. Jul 14, 2014

chipChocolate

I have a list of numbers x = [1, 11, 21, 1211, 111221,...], I need to find the 31st number in that list.

2. Jul 14, 2014

micromass

Hint: Look and say

Hint 2: 11 should not be seen as "eleven" but rather as individual ones.

3. Jul 14, 2014

pasmith

It could be anything. Truncating a sequence loses all information about subsequent terms.

Are you told how to construct the $n$th term, given the values of previous terms? If so, you need to do that.

4. Jul 14, 2014

chipChocolate

The actual question is to find the length of the 31st term.

Last edited: Jul 14, 2014
5. Jul 14, 2014

micromass

You need to recognize the pattern first. See Post #2.

6. Jul 14, 2014

xiavatar

Hint: The next term says something, quite literally, about the previous term.

7. Jul 14, 2014

chipChocolate

Thanks for the hint, I finally got it.

8. Jul 14, 2014

HakimPhilo

The problem with this type of questions is that they have more than one answer in general. For this particular sequence we have 3 possibilities that can be found at OEIS.