Group algebras acting on the space of solutions of a special double confluent Heun equation

We study properties of the space $\boldsymbol{\Omega}$ of solutions of a special double confluent Heun equation closely related to the model of a overdamped Josephson junction. We describe operators acting on $\boldsymbol{\Omega}$ and relations in the algebra $\mathcal{A}$ generated by them over the real number field. The structure of $\mathcal{A}$ depends on parameters. We give conditions under which $\mathcal{A}$ is isomorphic to a group algebra and describe two corresponding group structures.