Describes connections between the exponential functions and the additive group of real numbers (Fourier analysis), Legendre and Jacobi polynomials and representations of the group $SU(2)$, and the hypergeometric function and representations of the group $SL(2, R)$, as well as many other classes of special functions
Naum Yakovlevich Vilenkin, Russian: Наум Яковлевич Виленкин, was a Soviet mathematician, an expert in combinatorics. He is best known as the author of many books in recreational mathematics aimed at middle and high school students.