Macroeconomics for Mathematicians I'm coming from a math background (so my mind is set up for Definitions-Observation-Lemma-Proof frameworks) and looking for recommendations of a Macroeconomics textbook mainly devoted to growth models and foreign exchange rates. 

Any recommendations?
I really think a great place to start in general is Olivier Blanchard's "Macroeconomics". However, this is an economics undergraduate text and may not be optimal for a mathematician, especially given the structure you expect.

More to your taste may be the following standard texts:

"Introduction to modern economic growth" by Daron Acemoglu.

"Recursive Macroeconomic Theory" by Lars Ljungqvist and Thomas J. Sargent

"Recursive Methods in Economic Dynamics" by Nancy L. Stokey, Robert E. Lucas and Edward C. Prescott 

"Foundations of international macroeconomics" by Maurice Obstfeld and Kenneth Rogoff. A bit old by now, but a classic and a good place to start for international economic topics. Alternatively, try:

"Open Economy Macroeconomics" by Martín Uribe and Stephanie Schmitt-Grohé.