“…The calculation of the second regularized trace formula of the Sturm–Liouville operator with operator coefficient introduced in Adıgüzelov et al [29] where the second regularized trace formula of the Sturm–Liouville operator with the bounded operator coefficient given by Dirichlet boundary conditions is given. In Gül and Ceyhan [37], second regularized trace formulas were found for a fourth‐order differential operator with a bounded operator coefficient given with symmetric boundary conditions, and in Gül [32], second regularized trace formula are found for a high‐order differential operator with unbounded operator coefficient given with symmetric boundary conditions. In addition, in Gül and Gill [39, 40], the first regularized trace formulas for differential operators with bounded and unbounded operator coefficients, respectively, are calculated on a separable Banach space.…”