**Derrick H Lehmer** was an American mathematician who worked in number theory and in particular generalised Lucas's test for Mersenne primes.

- In 1927 Lehmer graduated from Berkeley with a B.A. degree in Physics and he went to the University of Chicago to undertake research for his doctorate in mathematics with L E Dickson as his supervisor.
- Lehmer was awarded his Master's Degree in 1929 and his doctorate, also from Brown University, in 1930.
- Lehmer's life over the next few years involved moving from place to place hoping for a permanent university post in the particularly difficult times of the Great Depression.
- After receiving his doctorate, Lehmer was awarded a National Research Fellowship and with this he spent 1930-31 at the California Institute of Technology and then 1931-32 at Stanford.
- After a spell at the Institute for Advanced Study at Princeton, where he held a second Fellowship, Lehmer moved to a more permanent post at Lehigh University in Pennsylvania.
- The Lehmers spent 1945-46 at the Aberdeen Proving Ground where Lehmer's task was to help set up and operate the ENIAC (Electronic Numerical Integrator and Calculator) computer.
- Nineteen faculty members of the University of California refused; Lehmer was one such faculty member.
- The assumption was that anyone who would not sign the oath must be a communist sympathiser and must be sacked, so Lehmer, as one of those who refused, lost his position.
- For Lehmer, however, the problem was not so acute for he was able to take up the post of Director of the National Bureau of Standards' Institute for Numerical Analysis for the time that he was unable to hold his faculty position in Berkeley.
- After the courts proclaimed the oath to be unconstitutional, Lehmer was reinstated at Berkeley.
- Lehmer's Selected Papers published in 1981 gives a good indication of the range of topics on which he worked.
- Errata in the tables are listed, the sources being given in the cases of errata previously printed; Lehmer's contributions in the way of new indications of errata are notable.
- Lehmer was awarded an honorary degree from Brown University in 1980.
- Lehmer lectured at the International Conference on Computers and Mathematics held at Stanford University in 1986.
- Let us mention a number of other topics for which Lehmer will be remembered.
- One must be the Lucas-Lehmer primality test which uses the Fermat congruence, and in particular his application to testing whether a Mersenne number was prime.
- Luck, however, often plays a large role in determining how famous a mathematician will become, and Lehmer's attack on the Riemann Hypothesis only provided evidence that the hypothesis was true whereas had the world been different it might have yielded a counterexample.

Born 23 February 1905, Berkeley, California, USA. Died 22 May 1991, Berkeley, California, USA.

View full biography at MacTutor

Origin Usa

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive