Building pseudoprimes with a large number of prime factors

We extend the method due originally to Löh and Niebuhr for the generation of Carmichael numbers with a large number of prime factors to other classes of pseudoprimes, such as Williams's pseudoprimes and elliptic pseudoprimes. We exhibit also some new Dickson pseudoprimes as well as superstrong Dickson pseudoprimes.On leave from the French Department of Defense, Délégation Générale pour l'Armement     

Measurement of Radon Exhalation from Soil - Development of the Method and Preliminary Results

The experimental method is developed, and the investigations are conducted with the use of different radon detectors. The dependence of exhalation intensity on the geological structure of surface layer is shown. The high value of the exhalation rate is established in the vicinity of abandoned settling pond of a coal mine.     

The Persistence of the Pastoral

Architect, animator and educator Nic Clear challenges the contemporary notion of the pastoral to go beyond the simplistic binary opposites of the untainted rural idyll and the industrialised city. He explores how the narratives of the pastoral have provided a mainstay for science fiction and how this can be used to re-imagine nature itself with the aid of advanced biotechnologies to create new architectures for the 21st century.     

广义Lucas数列的一些恒等式的证明

利用广义Lucas数列的性质,证明了广义Lucas数的一些求和公式。     

广义高阶Fibonacci数和Lucas数的计算公式

给出了广义的Fibonacci数和Lucas数一般定义,得出了几个恒等式,并得到了经典Fi-bonacci数和Lucas数的计算公式.     

Primality testing of large numbers in Maple

Primality testing of large numbers is very important in many areas of mathematics, computer science and cryptography, and in recent years, many of the modern primality testing algorithms have been incorporated in Computer Algebra Systems (CAS) such as Axiom and Maple as a standard. In this paper, we discuss primality testing of large numbers in Maple V Release 3, a Maple version newly released in 1994. Our computation experience shows that the Maple primality testing facility isprime, based on a combined use of a strong pseudoprimality test and a Lucas test, is efficient and reliable.     

关于Lucas数的一类行列式的计算

研究了一类由Lucas数组成的行列式Ln(m,k，l)的计算问题，证明了当m≤n-2时有恒等式Ln(m，k，l)=0，当m=n-1时给出了一个计算其值的公式。     

基于原模图的8环QC-LDPC码构造方法

针对当前准循环低密度奇偶校验(Quasi-Cyclic Low-Density Parity-Check, QC-LDPC)码存在短环及纠错性能不够好的问题,基于原模图提出一种新颖的QC-LDPC码构造方法。该方法选择码长码率可灵活调整的原模图作为基矩阵,再结合具有特殊性质的卢卡斯数列和等差数列,通过原模图的低译码门限和数列的特殊性质,构造校验矩阵环长至少为8,且所需存储空间少,易于硬件实现。仿真结果表明：该方法构造的PLA-QC-LDPC(2400,1200)码与同等码长码率中基于卢卡斯数列和最大公约数序列的可快速编码的非规则LG-QC-LDPC码、基于素数和乘法表构造的PM-QC-LDPC码以及基于原模图和消除基本陷阱集的非规则PL-QC-LDPC码相比,净编码增益均有一定程度的提高。     

On strong Dickson pseudoprimes

It is known that the Lucas sequenceV _n(,c)=aⁿ + bⁿ,a, b being the roots ofx ² – x + c=0 equals the Dickson polynomial .^n–2i Lidl, Müller and Oswald recently defined a number b to be a strong Dickson pseudoprime to the parameterc (shortlysDpp(c)) if [itg_n(b, c)b modn for all b. These numbers seem to be very appropriate for a fast probabilistic prime number test. In generalizing results of the above mentioned authors a criterion is derived for an odd composite number to be ansDpp(c) for fixedc. Furthermore the optimal parameterc for the prime number test is determined.     

涉及广义Fibonacci和Lucas数的组合恒等式

研究了二阶常系数线性齐次递归序列,利用发生函数和积分的方法,通过比较关于发生函数的恒等式左右两端的系数,建立了一系列涉及广义Fibonacci和Lucas数的多重和的组合恒等式.