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Homework Help: Generate a function from a list of numbers

  1. Jul 14, 2014 #1
    I have a list of numbers x = [1, 11, 21, 1211, 111221,...], I need to find the 31st number in that list.
  2. jcsd
  3. Jul 14, 2014 #2
    Hint: Look and say

    Hint 2: 11 should not be seen as "eleven" but rather as individual ones.
  4. Jul 14, 2014 #3


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    Homework Helper

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

    Are you told how to construct the [itex]n[/itex]th term, given the values of previous terms? If so, you need to do that.
  5. Jul 14, 2014 #4
    The actual question is to find the length of the 31st term.
    Last edited: Jul 14, 2014
  6. Jul 14, 2014 #5
    You need to recognize the pattern first. See Post #2.
  7. Jul 14, 2014 #6
    Hint: The next term says something, quite literally, about the previous term.
  8. Jul 14, 2014 #7
    Thanks for the hint, I finally got it.
  9. Jul 14, 2014 #8
    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.
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