2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/143676By considering the fundamental equation $x=y-y^2=z-z^3$, Somos conjectured that the Hankel determinants for the generating series $y(z)$ are the Somos-4 numbers. We prove this conjecture by using the quadratic transformation for Hankel determinants of Sulanke and Xin.3 pagesCombinatorics15A15; 30B70text