Abstract We show that the number of 5‐isogenies of elliptic curves defined over with naive height bounded by is asymptotic to for some explicitly computable constant . This settles the asymptotic count of rational points on the genus zero modular curves as moduli stacks. We leverage an explicit ‐isomorphism between the stack and the generalized Fermat equation with ‐action of weights .
Arango‐Piñeros et al. (2026) studied this question.