On the Expansion of the Parabolic Cylinder Function in a Series of the Product of Two Parabolic Cylinder Functions

Various forms of Addition Theorems have been since then given by various writers like Messrs. Gorakh Prasad, Dhar and Shastri, and Dhar, but most of these forms like (1) are true only for integral values of n. In a paper published in the Bulletin of the Calcutta Mathematical Society (Vol. 26, 1934), Dr. Dhar, however, obtained by "the contour method" an expression for D_n(x+y).