First sign changes of modular forms for general level N

초록

Let f(z)=∑n>0a(n)qn be a cusp form of weight k on Γ0(N) with real Fourier coefficients a(n). When N is squarefree, Choie and Kohnen gave a bound that the first sign change of a(n) occurs, and recently it was improved by He and Zhao. In this paper, we compute a bound for the first sign change problem for arbitrary N. © 2023 Elsevier Inc.

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