Flath D. Introduction to Number Theory 2003

Textbook in PDF format

On historical and mathematical grounds alike, number theory has earned a place in the curriculum of every mathematics student. This clear presentation covers the elements of number theory, with stress on the basic topics concerning prime numbers and Diophantine equations (especially quadratic equations in two variables). Topics covered include distribution of primes, unique factorization, reduction of positive definite quadratic forms, the Kronecker symbol, continued fractions, and what Gauss did