Understanding telescoping series

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jinksys
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I understand that if given the following series:

[tex]\sum _{n=1}^{\infty } \frac{1}{n(n+3)}[/tex]

I can break it up using partial fraction decomposition into:

[tex]\sum _{n=1}^{\infty } \frac{1}{3n}-\frac{1}{3n+9}[/tex]

If I start listing the values of [tex]n_1,n_2[/tex], etc, I can see the cancellation pattern and find the sum.

This process seems tedious, is there another way of doing these problems?

Wikipedia says:

* Let k be a positive integer. Then

[tex]\sum^\infty_{n=1} {\frac{1}{n(n+k)}} = \frac{H_k}{k}[/tex]

where Hk is the kth harmonic number. All of the terms after 1/(k − 1) cancel.

But I'm not sure what the 1/(k - 1) means, nor do I understand the harmonic number bit either.
 
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I think that what you are doing is correct, and probably the intended method to use. Sometimes you just got to go ahead and brute force your way through it.