First overtones of the crustal torsional oscillations with ℓ = 2 (solid line) and ℓ = 10 (dashed line) are shown as functions of ς given by Eq. (2) for three neutron star models with (M, R, M/R) = (1.4 M_⊙, 14 km, 0.146), (1.6 M_⊙, 12 km, 0.197), and (1.8 M_⊙, 10 km, 0.266). The top panel corresponds to N_s/N_d = 0, while the bottom panel to N_s/N_d = 1. In both panels, for reference, we draw (with a shaded thick line) the lowest QPO frequency found in GRB 200415A; i.e., 835.9 Hz (Castro-Tirado et al. 2021).