Authors: R. Conte ^1,2

• 1 Ecole Normale Supérieure Paris-Saclay [ENS Paris Saclay]
• 2 Department of Mathematics, The University of Hong Kong

A seventh order ordinary differential equation (ODE) arising by reduction of the Drinfeld-Sokolov hierarchyis shown to be identical to a similarity reduction of an equationin the hierarchy of Sawada-Kotera.We also exhibit its link with a particular F-VI,a fourth order ODE isolated by Cosgrove which is likely to define a higher order Painlevé function.