Counterexamples to the I(3)⊂I2 containment

The purpose of this short note is to show that there is in general no containmentI(3)⊂I2 for an ideal I of points in P2. This answers in the negative a question asked by Huneke and generalized by Harbourne. The sets of points constituting counterexamples come from the dual of the Hesse configuration and more generally from Fermat arrangements.