Add Line Breaks to Concate

I am using Sugar On Demand Pro. I have the ability to create calculated fields for a text area I am working on. I want to know how I can create line breaks between items.
Here is an example:
concat($first_name_c," ",$last_name_c)

I wish for the result to be as :
John 
Doe

I have tried basic php and html in there, but I just can not seem to break lines. Any suggestions on how to get that in there?