Numerical investigations related to the L-series of certain elliptic curves.

As the title indicates, the authors make computations around the Birch and Swinnerton-Dyer conjecture for the family x\sp 3+y\sp 3=m, m\in \bbfN, in the range m≤ 70000. They compute approximations of L(1) and L'(1). They show that the density of curves with a zero of order ≥ 2 (resp. ≥ 3) does not seem to be 0 as expected by the experts. Using these approximations as well as the Birch and Swinnerton-Dyer conjecture, the authors compute the order of the Tate-Shafarevich group. The results are presented graphically. Finally, a tentative analogue of the Cohen-Lenstra heuristic is presented and discussed but, as the authors observe the recipe does not seem to work in this case