MATH 341 is an upper division mathematics class taught at CSULB. In it's course description it defines the class as dealing with "[d]ivisibility, congruences, number theoretic functions, Diophantine equations, primitive roots, continued fractions ... [and w]riting proofs."
This page will deal specifically with the class I had, taught by Professor Linda Byun.
The textbook she used was Elementary Number Theory (7th ed.) by David M. Burton.