Jacques Touchard

Jacques André Charles Touchard (1885–1968) was a French mathematician. In 1953, he proved that an odd perfect number must be of the form ${\displaystyle 12k+1}$ or ${\displaystyle 36k+9}$. In combinatorics and probability theory, he introduced the Touchard polynomials. He is also known for his solution to the ménage problem of counting seating arrangements in which men and women alternate and are not seated next to their spouses.