Maji, B.Sathyanarayana, S.Shankar, B.R.2026-02-042022Results in Mathematics, 2022, 77, 3, pp. -14226383https://doi.org/10.1007/s00025-022-01655-yhttps://idr.nitk.ac.in/handle/123456789/22547Recently, Juyal, Maji, and Sathyanarayana have studied a Lambert series associated with a cusp form over the full modular group and the Möbius function. In this paper, we investigate the Lambert series ∑n=1∞[af(n)ψ(n)∗μ(n)ψ′(n)]exp(-ny), where a<inf>f</inf>(n) is the nth Fourier coefficient of a cusp form f over any congruence subgroup, and ψ and ψ′ are primitive Dirichlet characters. This extends the earlier work to the case of higher level subgroups and also gives a character analogue. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.cusp formsDirichlet L-functionLambert seriesnon-trivial zerosRiemann zeta function