Table 2 Numerical approximations to the first four eigenvalues of problem (24)–(25) according to \(E_{\delta, \theta } ( z) =\sum_{k = 0}^{750}\frac{z^{k}}{\Gamma ( \delta k + \theta ) }\). Eigenvalues correspond to eigenfunction \(f ( 0.5 )\)

α

\(\lambda_{1}\)

\(\lambda_{2}\)

\(\lambda_{3}\)

\(\lambda_{4}\)