Let $f$ be a Maass newform of weight 0 on $\Gamma_0(N)$ with spectral parameter $R$. If $f$ has even symmetry then as a function on the complex upper half plane it can be uniquely expressed in the form \[ f(x+iy) = \sum_{n=1}^\infty a_n\sqrt{y}K_{iR}(2\pi ny)\cos(2\pi nx), \] where $K_{iR}(\cdot)$ denotes the $K$-Bessel function with parameter $\nu=iR$ and the $a_n$ are real numbers.

If $f$ has odd symmetry it can instead be written as
\[
f(x+iy) = \sum_{n=1}^\infty a_n\sqrt{y}K_{iR}(2\pi ny)\sin(2\pi nx).
\]
In both cases the real numbers $a_n$ are the **coefficients** of $f$ and are used to define its L-function $L(f,s)=\sum_{n=1}^\infty a_nn^{-s}$.

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- Review status: reviewed
- Last edited by Andrew Sutherland on 2024-01-12 19:40:41

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**History:**(expand/hide all)

- 2024-01-12 19:40:41 by Andrew Sutherland (Reviewed)
- 2020-09-17 14:53:35 by Andrew Sutherland (Reviewed)
- 2020-07-24 14:21:38 by David Farmer (Reviewed)
- 2020-07-22 17:38:50 by Andrew Sutherland (Reviewed)
- 2020-07-22 09:57:49 by Andrew Sutherland

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