Pierpont prime
(another Prime Pages' Glossary entries)
The Prime Glossary
Glossary: Prime Pages: Top 5000: Gauss' proved that you can subdivide a circle into n parts using a ruler (an unmarked straightedge) and a compass (which draws circles) if and only if n is a power of two times a product of distinct Fermat primes.  Later Pierpont [Pierpont1895] showed that you can divide a circle into n parts using origami (paper folding) if and only if n is a product of a power of two times a power of three times a distinct product of primes of the form 2n3m+1.  These primes are now called Pierpont primes.

Simple heuristics suggest that there should be finitely many Fermat primes, but infinitely many Pierpont primes.  In the following table we give a count of the numbers smaller Pierpont primes.

N Pierpont primes
below N
10,000 25
1016 125
1032 250
1064 505
Circles can be divided into the same numbers of parts using a straight edge, compass and an "angle trisector." 

See Also: FermatNumber

Related pages (outside of this work)


D. A. Cox and J. Shurman, "Geometry and number theory on clovers," Amer. Math. Monthly, 112:8 (2005) 682--704.  MR2167769
A. M. Gleason, "Angle trisection, the heptagon, and the triskaidecagon," Amer. Math. Monthly, 95:3 (1988) 185--194.  MR935432
R. K. Guy, Unsolved problems in number theory, Springer-Verlag, New York, NY, 1994.  ISBN 0-387-94289-0. MR 96e:11002 [An excellent resource! Guy briefly describes many open questions, then provides numerous references. See his newer editions of this text.]
G. E. Martin, Geometric constructions, Undergraduate Texts in Mathematics Springer-Verlag, New York, 1998.  pp. xii+203, ISBN 0-387-98276-0. MR1483895
J. Pierpont, "On an undemonstrated theorem of the Disquisitiones Aritmeticae," American Mathematical Society Bulletin,:2 (1895-1896) 77 - 83.

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