Journal of Integer Sequences, Vol. 28 (2025), Article 25.2.5

Some Remarks Concerning the Lucas-Lehmer Primality Test


E. L. Roettger
Department of General Education
Mount Royal University
4825 Mount Royal Gate SW
Calgary, AB T3E 6K6
Canada

H. C. Williams
Department of Mathematics and Statistics
University of Calgary
2500 University Drive NW
Calgary, AB T2N 1N4
Canada

Abstract:

In 1876 Lucas devised a test for the primality of Mersenne numbers Mn, where n ≡ 3 (mod 4). He did so by calculating a recursive sequence sk with sk+1 = sk2 – 2, using an initial value of s1 = 3. Later, Lehmer refined Lucas' techniques and constructed a test for all Mersenne numbers with odd n (n ≥ 3); again he used the sequence sk, but with an initial value of 4. We investigate what initial values can be used in similar primality tests and for which values of n they can be used to test Mn. We also present some computational results.


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(Concerned with sequences A001566 A003010 A018844 A135927.)


Received July 25 2024; revised version received September 27 2024; March 22 2025. Published in Journal of Integer Sequences, March 23 2025.


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