# Help with series

• Jul 17th 2013, 05:19 AM
Help with series
Hello everyone, I'm kind of new here so wasn't sure where to post a series problem.

How would one go about summing

$\displaystyle \sum_{i=0}^{\infty} \frac{1}{(3i)!}$

I've tried to find similarities between it and the taylor series of hyperbolic cosine, but it isn't really working. I've tried repeated integration to derive a result with the factorial in the denominator but again, I get a non-convergent integral. Any help would be appreciated, thank you.
• Jul 17th 2013, 10:32 AM
johng
Re: Help with series
Hi,
Your problem has a straight forward solution, but the details require some computation. The attachment shows how to solve the problem, but I left the algebraic details to you:

Attachment 28846