The **coefficient ring ** of a modular form is the subring of $\C$ generated by the coefficients $a_n$ of its $q$-expansion $\sum a_nq^n$. In the case of a newform the coefficients $a_n$ are algebraic integers and the coefficient ring is a finite index subring of the ring of integers of the coefficient field of the newform.
It is also known as the **Hecke ring**, since the $a_n$ are eigenvalues of Hecke operators.

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- Last edited by David Roe on 2018-09-29 02:33:32

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- 2018-09-29 02:33:32 by David Roe (Reviewed)