Searching for Stories About Our Universe Being Artificial

Hello, 

I am looking for either short stories or novels in which the central
theme is that our universe is an artifical creation of some outside
intelligence. I know that in years past I have read at least two short
stories employing this idea but can't recall authors or titles.  I'm
rather certain that one of the two appeared in Analog. 

My objective is to identify the origins of this concept and to look at
the different ways in which the issue has been addressed.

Any help would be greatly appreciated. 

Thanks. 

 
Best Regards, Jim
http://artsnova.com/blog