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Topic: more recurrence relations
Replies: 1   Last Post: Nov 7, 1999 2:08 PM

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Kathleen

Posts: 58
Registered: 12/6/04
more recurrence relations
Posted: Nov 5, 1999 6:35 PM
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I'm not very good with recurrence relations ... so I guess the only
way to get better is practice.

This is the qn I'm now having problems doing:

Suppose that we have 4 cent stamps, 6 cent stamps, and 10 cent stamps,
each in unlimited supply. Let f(n) be the number of ways of obtaining
n cents of postage if the order in which we put on stamps counts. For
example, f(4)=1 and f(8)=1 (two 4 cent stamps), while f(10)=3 (one 10
cent stamp, or a 4 cent stamp followed by a 6 cents stamp, or a 6 cent
stamp followed by a 4 cent stamp).

(a) If n >10, derive a recurrence for f(n).
(b) Use the recurrence of part a) to find the # of ways of obtaining
14 cents of postage. (... this is just f(14) right?)


Thank you for the help again :)
Kathleen





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