Robert Hermann Breusch was a German-American number theorist, the William J. Walker Professor of Mathematics at Amherst College.
Breusch was born in Freiburg, Germany, and studied mathematics both at the University of Freiburg and the University of Berlin.
In 1939, they left Chile for the United States, inviting Robert Frucht to take Breusch"s place at Santa María. After some years working again as a schoolteacher, Breusch found a position at Amherst College in 1943. He became the Walker professor in 1970, and retired to become an emeritus professor in 1973.
The Robert H. Breusch Prize in Mathematics, for the best senior thesis from an Amherst student, was endowed in his memory.
As a mathematician, Breusch was known for his new proof of the prime number theorem and for the many solutions he provided to problems posed in the American Mathematical Monthly. His thesis work combined Bertrand"s postulate with Dirichlet"s theorem on arithmetic progressions by showing that each of the progressions 3i + 1, 3i + 2, 4i + 1, and 4i + 3 (for i = 0, 1, 2, ) contains a prime number between x and 2x for every x ≥ 7.
He also wrote a calculus textbook, Calculus and Analytic Geometry with Applications (Prindle, Weber & Schmidt, 1969) with C. Stanley Ogilvy.