2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59556Formulas previously presented for the Casson-Walker invariant are generalized to Lescop's extension. These formulas in terms of linking numbers and surgery coefficients compute the change in Lescop's invariant under crossing changes in a framed link presenting a 3-manifold. This leads us to revisit an old formula for a coefficient of the Conway polynomial. Finally we compute Lescop's invariant of several lens spaces and deduce some values for Dedekind sums.15 pages, 18 figuresGeometric TopologyNumber Theory57M (primary), 11 (secondary)text