Unsolved Problems in Number Theory (Hardcover) (ISBN-13: 9780387208602)

From reviews of the first edition:

"...many talented young mathematicians will write their first papers starting out from problems found in this book." -Mathematical Reviews

Mathematics is kept alive by the appearance of new unsolved problems, problems posed from within mathematics itself, and also from the increasing number of disciplines where mathematics is applied. This book provides a steady supply of easily understood, if not easily solved, problems which can be considered in varying depths by mathematicians at all levels of mathematical maturity.