The following is a proof of convergence. I think it is a little more transparent than rudinreader's but due credit must be given to rudinreader as his proof provides the backbone for this one.
(1) The first thing of note is...
\frac{ log( log( n! ) ) }{ log(n) } \rightarrow 1
Which...
Sounds interesting.
Also I would like to see how you guys would go about proving convergence of the sequence.
The one thing I couldn't do was come up with a closed form expression for the value. The person who set the problem couldn't either so I didn't waste too much time on this.
I don't want to tell you how I solved the problem for a good reason. I found it to be quite interesting and I want to see other creative and unique ideas for solving it. If I tell you how I did it then I probably will not see other creative approaches.
Here is some carrot: a_4 = 2.1164259
Of course you will get overflow error if you compute it the naive way. The idea is to write it in a different form so you can calculate it without overflow.
I have already solved the problem. Just interested in what others have to say about it.
Can any of you solve this? :smile:
Firstly, some notation:
Let \Pi(x) = \Gamma(x+1) where \Gamma(x) is the usual gamma function i.e. an extension of the factorial to the complex numbers.
Let log^{n} (x) = log( log( \cdots log( x ) ) ) where log is applied n times to x e.g. log^{4} (x) = log(...