Factorization of some confluent Heun’s differential equations

This paper stands for a logic continuation of the previous work [A. Ronveaux, Factorization of the Heun’s differential operator, Appl. Math. Comput. 141 (2003) 177–184]. We propose a factorization of the confluent, double confluent and biconfluent Heun’s differential equations and investigate their solutions.