A Mathematical Olympiad Primer ((free)) -

: ((k - n - 1)(k + n + 1) = 4). Both factors have same parity (even), positive/negative cases → finite solutions. (Try finishing yourself.)

| Book | Purpose | |------|---------| | The IMO Compendium (various authors) | IMO problems 1959– onward | | Problem-Solving Strategies (Arthur Engel) | Deep, topic-based problem collection | | Euclidean Geometry in Mathematical Olympiads (Evan Chen) | Geometry gap filler | | Number Theory: Structures, Examples, and Problems (Titu Andreescu) | Deeper number theory | a mathematical olympiad primer