An explicit structure of the graded ring of modular forms of small level
arXiv:1108.3933
Abstract
In this paper, we study the explicit structure of the graded ring of elliptic modular forms for the congruence subgroup with N=1,2,3,4,5,6,7,8,9,10,12,16,18,25. More precisely, making use of some relations between Fourier expansions, we determine the ring by a quotient of the polynomial ring in several variables.