An Introductory Course in Elementary Number Theory
by Wissam Raji
Publisher: The Saylor Foundation 2013
Number of pages: 171
These notes serve as course notes for an undergraduate course in number theory. Proofs of basic theorems are presented in an interesting and comprehensive way that can be read and understood even by non-majors. The exercises are carefully chosen to broaden the understanding of the concepts.
Download or read it online for free here:
by Joseph H. Silverman - Pearson Education, Inc.
Introductory undergraduate text designed to entice non-math majors into learning some mathematics, while at the same time teaching them how to think mathematically. The exposition is informal, with a wealth of examples that are analyzed for patterns.
by Thomas Taylor, A. J. Valpy
The substance of all that has been written on this subject by Nicomachus, Iamblichus, and Boetius, together with some particulars respecting perfect, amicable, and other numbers, which are not to be found in the writings of modern mathematicians.
by William Stein - Springer
Textbook on number theory and elliptic curves. It discusses primes, factorization, continued fractions, quadratic forms, computation, elliptic curves, their applications to algorithmic problems, and connections with problems in number theory.
by Leo Moser - The Trillia Group
The book on elementary number theory: compositions and partitions, arithmetic functions, distribution of primes, irrational numbers, congruences, Diophantine equations; combinatorial number theory, and geometry of numbers.