Lothar Collatz
Lothar Collatz (July 6, 1910 - September 26, 1990) was a German mathematician best known for formulating the puzzling Collatz problem, also known as the \(3n + 1\) conjecture. This problem, though simple to state —involving a sequence of operations on a natural number until reaching 1— has resisted formal proof for decades, making it one of the most intriguing open questions in recreational mathematics and number theory. Beyond this, Collatz also made significant contributions to numerical analysis, linear algebra, and graph theory. His legacy endures in multiple areas of applied mathematics.