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A note on factorization of the Fermat numbers and their factors of the form 3 h 2 n + 1

Michal Křížek, Jan Chleboun (1994)

Mathematica Bohemica

We show that any factorization of any composite Fermat number F m = 2 2 m + 1 into two nontrivial factors can be expressed in the form F m = ( k 2 n + 1 ) ( 2 n + 1 ) for some odd k and , k 3 , 3 , and integer n m + 2 , 3 n < 2 m . We prove that the greatest common divisor of k and is 1, k + 0 m o d 2 n , m a x ( k , ) F m - 2 , and either 3 | k or 3 | , i.e., 3 h 2 m + 2 + 1 | F m for an integer h 1 . Factorizations of F m into more than two factors are investigated as well. In particular, we prove that if F m = ( k 2 n + 1 ) 2 ( 2 j + 1 ) then j = n + 1 , 3 | and 5 | .

A polynomial reduction algorithm

Henri Cohen, Francisco Diaz Y Diaz (1991)

Journal de théorie des nombres de Bordeaux

The algorithm described in this paper is a practical approach to the problem of giving, for each number field K a polynomial, as canonical as possible, a root of which is a primitive element of the extension K / . Our algorithm uses the L L L algorithm to find a basis of minimal vectors for the lattice of n determined by the integers of K under the canonical map.

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