As these examples show, the effort involved in finding the solutions to the Diophantine
equation y2 D x3 C d depends in a rather unpredictable way on the constant d.
Among the many results on this problem, some stand out. Euler showed that there
are no positive rational solutions apart from .2; 3/ when d D 1 using the method of
descent, and a long series of other special cases were solved by many other mathematicians
(see Dickson [7, Chap. XX] for the details). A snapshot of the state of
knowledge on this question in 1914 may be found in the work of Mordell [20], where
many but not all values of d for which there are no integral solutions are found.