22 research outputs found
Analogues of the Ramanujan--Mordell Theorem
The Ramanujan--Mordell Theorem for sums of an even number of squares is
extended to other quadratic forms and quadratic polynomials
Ramanujan type congruences for quotients of level 7 Klein forms
Klein forms are used to construct generators for the graded algebra of modular forms of level 7. Dissection formulas for the series imply Ramanujan type congruences modulo powers of 7 for a family of generating functions that subsume the counting function for 7-core partitions. The broad class of arithmetic functions considered here enumerate colored partitions by weights determined by parts modulo 7. The method is a prototype for similar analysis of modular forms of level 7 and at other prime levels. As an example of the utility of the dissection method, the paper concludes with a derivation of novel congruences for the number of representations by x^2+xy+2y^2 in exactly k ways