Divisor problems for restricted Fourier coefficients of modular forms

Yuk-Kam Lau, Wonwoong Lee

Let $d(n)$ be the number of divisors of $n$. We investigate the average value of $d(a_f(p){)}^r$ for $r$ a positive integer and $a_f(p)$ the $p$-th Fourier coefficient of a cuspidal…