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Homework Help: Finding a recurrence Relation

  1. Sep 22, 2012 #1
    Find a simple closed formula for the ordinary generating function of the sequence given by

    {a[itex]_{n}[/itex]]}n>=0 when a[itex]_{n}[/itex] is given by

    a[itex]_{n}[/itex] = 6 * 5^n - 5 * 3^n.

    My question is how do you find the recurrence relation a[itex]_{n}[/itex] = 6 * 5^n - 5 * 3^n.

    I don't know were to start.
  2. jcsd
  3. Sep 22, 2012 #2


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    Gold Member

    Why bother with finding a recurrence relation? Your sequence looks like a combination of two geometric sequences. What is the the generating function for each one? What do you get when you add the two generating functions together?
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