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First we write the series as a summation.
NOTE: our index starts at since will give us 1, which is not a value in our series.
In this problem, we will first need to come up with a general term for the series. Notice that the numerators of all terms are just multiples of - therefore, the general term will be . Then, notice that the denominators are factorials. That's why the denominator in the general term will be , and we have the series:
Now, we are trying to recognize a familiar power series similar to this one. Since there is an in the denominator, this ought to remind us of the power series for :
Notice that the counter in our sum starts at , while the power series starts at . Using this, we can now find the sum:
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