This article gives background on the program that Derick and Emma Lehmer were working on that weekend:On May 10, 2017, at 8:01 AM, Brian Berg <brianberg@gmail.com> wrote:A new story by John Markoff posted as a blog to the Computer History Museum's website. I did not find anything about this in the Thomas Haigh, et al. book ENIAC in Action book. Brian Berg
Liesbeth De Mol, Maarten Bullynck. A Week-End Off: The First Extensive Number-Theoretical Computation on the ENIAC. Lecture notes in computer science, springer, 2008, 5028, pp.158-167. <10.1007/978-3-540-69407-6 19>. <hal-01396832>
http://hal.univ-lille3.fr/hal-01396832