Chakraborty, KalyanKalyanChakrabortyJuyal, AbhishekAbhishekJuyalKumar, Shiv DattShiv DattKumarMaji, BibekanandaBibekanandaMaji2025-08-302025-08-302018-02-0110.1142/S17930421185001732-s2.0-85025159826http://repository.iitgn.ac.in/handle/IITG2025/22324Zagier's conjecture on the asymptotic expansion of the Lambert series Σn=1∞∞2(n)exp(-nz), where ∞(n) is the Ramanujan's tau function, was proved by Hafner and Stopple. Recently, Chakraborty, Kanemitsu and Maji have extended this result to any cusp forms over the full modular group. The goal of this paper is to extend the asymptotic behavior to cusp forms over any congruence subgroup of the full modular group.falseAsymptotic expansion | cusp form | Rankin-Selberg L -function | symmetric square L -functionArticle289-2991 February 20188arJournal8WOS:000416036500017