广义Carmichael数

设n是一个合数,Z_n表示模n的剩余类环,r(x)∈Z_n[x]是一个首一的k(>0)次不可约多项式。本文引入n是k阶摸r(x)的Carmichael数的定义,全体这样的数记为集C_(k,r)(x),由此给出k阶Carmichael数集:C_k={∪C_(k,r)(x)|r(x)过全体Z_n上的首一k次不可约多项式}。显然C_1表示通常的Carmichael数集。作者得到了n∈C_(k,r(x))的一个充要条件,进而得到n∈C_k的一个充要条件及n∈C_2的一个更易计算的充要条件,还证明了C_1(?)C_2以及|C_2|=∞。     

对一个问题的探究

张永栋老师在《巧作“抽屉”妙证一赛题》（见《中学数学月刊》98年第1期）一文中巧妙地解决了如下问题：在1～100这一百个自然数中，任取18个，证明一定存在四个数，其中有两个数之差等于另两个数之差（这里规定：差是大数减去小数之差）作者并提出了一个未解决的问题：对任取18个数，能否再减少些仍使命题成立？本文作出了肯定的回答，并给出了它的一般定理为叙述方便起见，先从这个实例谈起例在1～100这一百个自然数中，任取16个，证明一定存在四个数，其中有两个数之差等于另两个数之差（这里规定：差是指大数减去小数之差）．证国1—10…     

六阶图G与Sn的积图的交叉数

确定图的交叉数是NP．完全问题．目前已确定交叉数的六阶图与星图的笛卡尔积图极少。本文确定了—个六阶图G与星图5k积图的交叉数为Z（6,n）＋2n＋[n/2].     

素数阶循环图和经典Ramsey数R（4，n）的三个新下界

研究了素数阶循环圈的基本性质，提出了寻求有效参数构造正则循环圈的新方法，得到了3个经典Ramsey数的新下界：R（4，17）≥164，R（4，18）≥182，R（4，22）≥282．这前2个结果填补了关于Ramsey数综述[2]的上下界表中的2个空白，第3个结果超过了目前已知的最好下界R（4，22）≥258，     

一个包含Euler函数及k阶Smarandache ceil函数的方程及其正整数解

设k≥2为给定的整数．对任意正整数n,k阶Smarandache ceil函数Sk（n）定义为Sk（n）=min{x：x∈N,n｜x^k}．本文的主要目的是利用初等方法研究函数方程Sk（n）=Ф（n）的可解性,并给出该方程的所有正整数解,其中Ф（n）为Euler函数．     

"1"的一种无理分拆

众所周知，1在数域中占有极其重要的地位，它3（2 （5）的平方根）的平方根 3（2-（5）的平方根）的平方根=3（5 2（13）的平方根） 3（5-2（13）的平方根）=1这种共轭型的分拆使人觉得其形式对称而优美，然而这种形式的分拆究竟有多少个?它们属于有理还是无理分拆?下面的3个性质将完全回答所提问题。     

亚纯函数唯一性的Gross问题

F．Gross提出问题：能否找到两个（甚至一个）有穷集会Sj（j＝1；2），使得满足Ef（Sj）＝Eg（Sj）（j＝1，2）的任何两个整函数f和g必定恒等，这里Ef（Sj）表示Sj关于f的逆像，计重数．仅供助[6]对于亚纯函f，和g对此问题作了肯定的回答．本文以（S）和（S）代替EF（S）和Eg（S），对这个问题作了进一步的讨论，这里（S）是与Ef（S）相同的点集，但不计重教．     

Sierpinski gasket上Brown运动k重时的Hausdorff维数

设k≥2是正整数｛X（t），t≥0｝是SierpinskigasketG上的Brown运动，本文研究了｛X（t），t≥0｝k重时的Hausdorff维数，证明了：其中Mk＝｛（t1，t2…，tk）｝∈Rk：t1，t2，…，tk互不相同，使得X（t1）＝X（t2）＝…＝X（tk）｝，     

3阶非单谷Feigenbaum映射的拟极限集

一个从闭区间到自身的连续映射被称为3阶非单谷Feigenbaum映射,如果它是函数方程f~3(λx)=λf(x)的解．本文讨论了3阶非单谷Feigenbaum映射的拟极限集及其Hausdorff维数．3阶非单谷Feigenbaum映射必然产生混沌,混沌的产生使得拟极限集的存在性问题复杂化．文中采用分形几何中的知识方法证明了此类映射的拟极限集的存在性,并相应的对其Hausdorff维数作出了估计．最后给了一个具体的例子,说明确实存在这样的3阶非单谷Feigenbaum映射．     

关于不可约空间（II）

本文证明了：（１）Ｔ１完全的弱δθ－加细空间是遗传性不可约空间，肯定地回答了作者前论文《关于不可约空间》中的问题３；（２）闭、可数紧映射及、可数紧映射均保持点可数基。由后者可得Ａｒｈａｎｇｅｌ’ｓｋｉｉ的ＭＯＢＩ类的每一空间都是不可约空间，肯定地回答了上述论文中的问题８。     

The evaluation of

Numerical evidence relevant to the evaluation of the constant  in the conjectural distribution of three-prime Carmichael numbers of Granville and Pomerance (2001) is summarised.

     

Higher-order Carmichael numbers

We define a Carmichael number of order to be a composite integer such that th-power raising defines an endomorphism of every -algebra that can be generated as a -module by elements. We give a simple criterion to determine whether a number is a Carmichael number of order , and we give a heuristic argument (based on an argument of Erdos for the usual Carmichael numbers) that indicates that for every there should be infinitely many Carmichael numbers of order . The argument suggests a method for finding examples of higher-order Carmichael numbers; we use the method to provide examples of Carmichael numbers of order .

     

A new algorithm for constructing large Carmichael numbers

We describe an algorithm for constructing Carmichael numbers with a large number of prime factors . This algorithm starts with a given number , representing the value of the Carmichael function . We found Carmichael numbers with up to factors.

     

Density of Carmichael numbers with three prime factors

We get an upper bound of on the number of Carmichael numbers with exactly three prime factors.

     

Finding strong pseudoprimes to several bases. II

Define to be the smallest strong pseudoprime to all the first prime bases. If we know the exact value of , we will have, for integers , a deterministic efficient primality testing algorithm which is easy to implement. Thanks to Pomerance et al. and Jaeschke, the are known for . Upper bounds for were first given by Jaeschke, and those for were then sharpened by the first author in his previous paper (Math. Comp. 70 (2001), 863-872).

In this paper, we first follow the first author's previous work to use biquadratic residue characters and cubic residue characters as main tools to tabulate all strong pseudoprimes (spsp's) to the first five or six prime bases, which have the form with odd primes and ; then we tabulate all Carmichael numbers , to the first six prime bases up to 13, which have the form with each prime factor . There are in total 36 such Carmichael numbers, 12 numbers of which are also spsp's to base 17; 5 numbers are spsp's to bases 17 and 19; one number is an spsp to the first 11 prime bases up to 31. As a result the upper bounds for and are lowered from 20- and 22-decimal-digit numbers to a 19-decimal-digit number:

We conjecture that

and give reasons to support this conjecture. The main idea for finding these Carmichael numbers is that we loop on the largest prime factor and propose necessary conditions on to be a strong pseudoprime to the first prime bases. Comparisons of effectiveness with Arnault's, Bleichenbacher's, Jaeschke's, and Pinch's methods for finding (Carmichael) numbers with three prime factors, which are strong pseudoprimes to the first several prime bases, are given.

     

Prime witnesses in the Shor algorithm and the Miller-Rabin algorithm

We prove that prime witnesses in the Miller-Rabin algorithm coincide with those in the Shor algorithm which satisfy the condition of Fermat’s little theorem. We describe the set of natural numbers, whose prime witnesses in the Miller-Rabin algorithm coincide with those in the Shor algorithm. We find all such numbers less than 100,000,000 and experimentally study the rate of increase of the ratio of the quantity of such numbers to the quantity of Carmichael numbers.     

Some generalizations of the Apostol-Genocchi polynomials and the Stirling numbers of the second kind

Recently, the authors introduced some generalizations of the Apostol-Bernoulli polynomials and the Apostol-Euler polynomials (see [Q.-M. Luo, H.M. Srivastava, J. Math. Anal. Appl. 308 (2005) 290-302] and [Q.-M. Luo, Taiwanese J. Math. 10 (2006) 917-925]). The main object of this paper is to investigate an analogous generalization of the Genocchi polynomials of higher order, that is, the so-called Apostol-Genocchi polynomials of higher order. For these generalized Apostol-Genocchi polynomials, we establish several elementary properties, provide some explicit relationships with the Apostol-Bernoulli polynomials and the Apostol-Euler polynomials, and derive various explicit series representations in terms of the Gaussian hypergeometric function and the Hurwitz (or generalized) zeta function. We also deduce their special cases and applications which are shown here to lead to the corresponding results for the Genocchi and Euler polynomials of higher order. By introducing an analogue of the Stirling numbers of the second kind, that is, the so-called λ-Stirling numbers of the second kind, we derive some basic properties and formulas and consider some interesting applications to the family of the Apostol type polynomials. Furthermore, we also correct an error in a previous paper [Q.-M. Luo, H.M. Srivastava, Comput. Math. Appl. 51 (2006) 631-642] and pose two open problems on the subject of our investigation.     

高阶退化Bernoulli数和多项式

本文研究了高阶退化Berrioulli数和多项式的两个显明公式，得到了一个包含高阶Bemoulli数和Stirling数的恒等式，并推广了F．H．Howard，S．Shirai和K．I．Sato的结果。     

Numerical solution of a system of fourth order boundary value problems using variational iteration method

In this paper, the variational iteration method is used to solve a system of fourth order boundary value problems associated with obstacle, unilateral and contact problems. Numerical solution obtained by the method is of high accuracy. Moreover, the higher-order derivatives of numerical solution can also approximate the higher-order derivatives of exact solution well. Five examples compared with those considered by Siddiqi and Akram [S.S. Siddiqi, G. Akram, Numerical solution of a system of fourth order boundary value problems using cubic non-polynomial spline method, Applied Mathematics and Computation 190 (2007) 652–661] show that the method is more efficient.