An Open Door to Number Theory - Duff Campbell - Bog - American Mathematical Society - Plusbog.dk
A well-written, inviting textbook designed for a one-semester, junior-level course in elementary number theory. The approach throughout is geometric and intuitive; there are over 400 carefully designed exercises, which include a balance of calculations, conjectures, and proofs. There are also nine substantial student projects on topics not usually covered in a first-semester course.