Wronskian formula for confluent second-order supersymmetric quantum mechanics

The confluent second-order supersymmetric quantum mechanics, with factorization energies ε1, ε2 tending to a single ε-value, is studied. We show that the Wronskian formula remains valid if generalized eigenfunctions are taken as seed solutions. The confluent algorithm is used to generate SUSY partners of the Coulomb potential.