Viggo Brun (13 October 1885 – 15 August 1978) was a Norwegian professor, mathematician and number theorist.

[1] In 1915, he introduced a new method, based on Legendre's version of the sieve of Eratosthenes, now known as the Brun sieve, which addresses additive problems such as Goldbach's conjecture and the twin prime conjecture.

He developed a multi-dimensional continued fraction algorithm in 1919–1920 and applied this to problems in musical theory.

He also served as praeses of the Royal Norwegian Society of Sciences and Letters in 1946.

[4] He retired in 1955 at the age of 70 and died in 1978 (at 92 years-old) at Drøbak in Akershus, Norway.