Smooth values of polynomials

Given $f\in \mathbb{Z}[t]$ of positive degree, we investigate the existence of auxiliary polynomials $g\in \mathbb{Z}[t]$ for which $f(g(t))$ factors as a product of polynomials of small relative degree. One consequence of this work shows that for any quadratic polynomial $f\in\mathbb{Z}[t]$ and any $\epsilon > 0$, there are infinitely many $n\in\mathbb{N}$ for which the largest prime factor of $f(n)$ is no larger than $n^{\epsilon}$

A Reverse Sierpinski Number Problem

A generalized Sierpinski number base b is an integer k\u3e1 for which gcd(k+1,b-1)=1, k is not a rational power of b, and kbn+1 is composite for all n\u3e0. Given an integer k\u3e0, we will seek a base b for which k is a generalized Sierpinski number base b. We will show that this is not possible if k is a Mersenne number. We will give an algorithm which will work for all other k provided that there exists a composite in the sequence {(k2m+1)/gcd(k+1,2)} for m ≥ 0

Factoring with the quadratic sieve on large vector computers

AbstractThe results are presented of experiments with the multiple polynomial version of the quadratic sieve factorization method on a CYBER 205 and on a NEC SX-2 vector computer. Various numbers in the 50–92 decimal digits range have been factorized, as a contribution to (i) the Cunningham project, (ii) Brent's table of factors of Mersenne numbers, and (iii) a proof by Brent and G. Cohen of the non-existence of odd perfect numbers below 10200. The factorized 92-decimal digits number is a record for general purpose factorization methods

On a conjecture of Wilf

Let n and k be natural numbers and let S(n,k) denote the Stirling numbers of the second kind. It is a conjecture of Wilf that the alternating sum \sum_{j=0}^{n} (-1)^{j} S(n,j) is nonzero for all n>2. We prove this conjecture for all n not congruent to 2 and not congruent to 2944838 modulo 3145728 and discuss applications of this result to graph theory, multiplicative partition functions, and the irrationality of p-adic series.Comment: 18 pages, final version, accepted for publication in the Journal of Combinatorial Theory, Series

A New Family of Pairing-Friendly elliptic curves

International audienceThere have been recent advances in solving the finite extension field discrete logarithm problem as it arises in the context of pairing-friendly elliptic curves. This has lead to the abandonment of approaches based on supersingular curves of small characteristic, and to the reconsideration of the field sizes required for implementation based on non-supersingular curves of large characteristic. This has resulted in a revision of recommendations for suitable curves, particularly at a higher level of security. Indeed for a security level of 256 bits, the BLS48 curves have been suggested, and demonstrated to be superior to other candidates. These curves have an embedding degree of 48. The well known taxonomy of Freeman, Scott and Teske only considered curves with embedding degrees up to 50. Given some uncertainty around the constants that apply to the best discrete logarithm algorithm, it would seem to be prudent to push a little beyond 50. In this note we announce the discovery of a new family of pairing friendly elliptic curves which includes a new construction for a curve with an embedding degree of 54

Smooth values of polynomials

Given f Z[t] of positive degree, we investigate the existence of auxiliary polynomials g Z[t] for which factors as a product of polynomials of small relative degree. One consequence of this work shows that for any quadratic polynomial f Z[t] and any ϵ > 0, there are infinitely many for which the largest prime factor of f(n) is no larger than n