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Homework Help: Recurrence relation

  1. Aug 23, 2011 #1
    Use a recurrence relation to find the number of ways that stamps that have a value of 1 cent , 2 cents and a 3 cents can add up to eight cents.

    How exactly do you go about solving a problem like this with out writing a program to find all the possibilities?

    The answer given is 81, but I have know Idea how to get it.
  2. jcsd
  3. Aug 24, 2011 #2

    Ray Vickson

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    How would you interpret the coefficient of x^8 in the expansion of (x+x^2+x^3)^n?

  4. Aug 24, 2011 #3
    Would that be the number of times a certain combination happens?
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