The twenty-fourth Fermat number is composite

Authors:
Richard E. Crandall, Ernst W. Mayer and Jason S. Papadopoulos

Journal:
Math. Comp. **72** (2003), 1555-1572

MSC (2000):
Primary 11Y11, 11Y16, 68Q25, 11A51

Published electronically:
December 6, 2002

MathSciNet review:
1972753

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Abstract | References | Similar Articles | Additional Information

Abstract: We have shown by machine proof that is composite. The rigorous Pépin primality test was performed using independently developed programs running simultaneously on two different, physically separated processors. Each program employed a floating-point, FFT-based discrete weighted transform (DWT) to effect multiplication modulo . The final, respective Pépin residues obtained by these two machines were in complete agreement. Using intermediate residues stored periodically during one of the floating-point runs, a separate algorithm for pure-integer negacyclic convolution verified the result in a ``wavefront'' paradigm, by running simultaneously on numerous additional machines, to effect piecewise verification of a saturating set of deterministic links for the Pépin chain. We deposited a final Pépin residue for possible use by future investigators in the event that a proper factor of should be discovered; herein we report the more compact, traditional Selfridge-Hurwitz residues. For the sake of completeness, we also generated a Pépin residue for , and via the Suyama test determined that the known cofactor of this number is composite.

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Additional Information

**Richard E. Crandall**

Affiliation:
Center for Advanced Computation, Reed College, Portland, Oregon 97202

Email:
crandall@reed.edu

**Ernst W. Mayer**

Affiliation:
Department of Mech. & Aerospace Engineering, Case Western Reserve University, Cleveland, Ohio 44106

Address at time of publication:
10190 Parkwood Dr. Apt. 1, Cupertino, CA 95014

Email:
ewmayer@aol.com

**Jason S. Papadopoulos**

Affiliation:
Department of Elec. & Comp. Engineering, University of Maryland, College Park, Maryland 20742

Email:
jasonp@boo.net

DOI:
https://doi.org/10.1090/S0025-5718-02-01479-5

Received by editor(s):
October 14, 1999

Received by editor(s) in revised form:
September 5, 2001

Published electronically:
December 6, 2002

Article copyright:
© Copyright 2002
American Mathematical Society