Divisibility Properties of Coefficients of Level $p$ Modular Functions   for Genus Zero Primes
  Lehner's 1949 results on the $j$-invariant showed high divisibility of the function's coefficients by the primes $p\in\{2,3,5,7\}$. Expanding his results, we examine a canonical basis for the space of level $p$ modular functions holomorphic at the cusp 0. We show that the Fourier coefficients of these functions are often highly divisible by these same primes. 
Nickolas Andersen and Paul Jenkins
math.NT