On this day in 1742, Leonard Euler claimed in a letter to Goldbach that prime numbers of the form 4n+ 1 are represented uniquely as a sum of two squares.
He also mentioned that 641 divides 232+1232+1232+1, thereby disproving Fermat's claim that all the so-called numbers Fermat numbers Fn=22n+1𝐹𝑛=22𝑛+1Fn=22n+1 are prime. Years later we have not found another with n > 4 which is prime.
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Born:
1748: Dominique Cassini Ⓟ
1791: Félix Savart Ⓟ
1846: Eugen Netto Ⓟ
1856: Cargill Knott Ⓟ
1868: Geoffrey Bennett Ⓟ
1876: Anton Davidoglu Ⓟ
1880: Rudolf Fueter Ⓟ
1900: Gheorghe Vrănceanu Ⓟ
1923: Murray Macbeath Ⓟ
1958: Abigail Thompson Ⓟ
Died:
1817: Li Rui
1919: John William Strutt Ⓟ
1960: Albert Châtelet Ⓟ
1972: Yuri Vladimirovich Linnik Ⓟ
2002: Claude Berge Ⓟ
2019: Mitchell Feigenbaum Ⓟ
