On an application of the large sieve: Shifted prime numbers, which have no prime divisors from a given arithmetical progression

1970 ◽  
Vol 21 (1-2) ◽  
pp. 151-173 ◽  
Author(s):  
I. Kátai
Keyword(s):  
Prime Numbers ◽  
Large Sieve ◽  
Arithmetical Progression ◽  
Prime Divisors ◽  
Shifted Prime

On prime numbers in an arithmetical progression

1958 ◽  
Vol 4 (1) ◽  
pp. 57-70 ◽  
Author(s):  
Stanisław Knapowski
Keyword(s):  
Prime Numbers ◽  
Arithmetical Progression

A Variation on the Algorithm for GCD and LCM

1982 ◽  
Vol 30 (3) ◽  
pp. 46
Author(s):  
Verna M. Adams
Keyword(s):  
Prime Numbers ◽  
Prime Divisors ◽  
Common Multiple ◽  
Least Common Multiple ◽  
Prime Factors

An algorithm sometimes presented for finding the least common multiple (LCM) of two numbers uses tbe technique of simultaneously finding the prime factors of the numbers. This technique is shown in figure 1. Both numbers are checked for divisibility by 2, then by 3, by 5, and so on. If the divisor does not divide one of the numbers, the number is written on the next line as shown in steps 4 and 5. This process continues until all numbers to the left and on the bottom are prime numbers, or it can be continued, as shown in figure 1, until the numbers across the bottom are all ones. The least common multiple is the product of all of the prime divisors. Thus, LCM (80, 72) = 24 · 32 · 5.

scholarly journals Some interesting tasks from the classical number theory

2020 ◽  
pp. 150-188
Author(s):  
Zurab Agdgomelashvili ◽  
Keyword(s):  
Number Theory ◽  
Prime Number ◽  
Prime Numbers ◽  
Natural Numbers ◽  
Prime Divisors ◽  
Problem Class

The article considers the following issues: – It’s of great interest for p and q primes to determine the number of those prime number divisors of a number 1 1 pq A p    that are less than p. With this purpose we have considered: Theorem 1. Let’s p and q are odd prime numbers and p  2q 1. Then from various individual divisors of the 1 1 pq A p    number, only one of them is less than p. A has at least two different simple divisors; Theorem 2. Let’s p and q are odd prime numbers and p  2q 1. Then all prime divisors of the number 1 1 pq A p    are greater than p; Theorem 3. Let’s q is an odd prime number, and p N \{1}, p]1;q] [q  2; 2q] , then each of the different prime divisors of the number 1 1 pq A p    taken separately is greater than p; Theorem 4. Let’s q is an odd prime number, and p{q1; 2q1}, then from different prime divisors of the number 1 1 pq A p    taken separately, only one of them is less than p. A has at least two different simple divisors. Task 1. Solve the equation 1 2 1 z x y y    in the natural numbers x , y, z. In addition, y must be a prime number. Task 2. Solve the equation 1 3 1 z x y y    in the natural numbers x , y, z. In addition, y must be a prime number. Task 3. Solve the equation 1 1 z x y p y    where p{6; 7; 11; 13;} are the prime numbers, x, y  N and y is a prime number. There is a lema with which the problem class can be easily solved: Lemma ●. Let’s a, b, nN and (a,b) 1. Let’s prove that if an  0 (mod| ab|) , or bn  0 (mod| ab|) , then | ab|1. Let’s solve the equations ( – ) in natural x , y numbers: I. 2 z x y z z x y          ; VI. (x  y)xy  x y ; II. (x  y)z  (2x)z  yz ; VII. (x  y)xy  yx ; III. (x  y)z  (3x)z  yz ; VIII. (x  y) y  (x  y)x , (x  y) ; IV. ( y  x)x y  x y , (y  x) ; IX. (x  y)x y  xxy ; V. ( y  x)x y  yx , (y  x) ; X. (x  y)xy  (x  y)x , (y  x) . Theorem . If a, bN (a,b) 1, then each of the divisors (a2  ab  b2 ) will be similar. The concept of pseudofibonacci numbers is introduced and some of their properties are found.

scholarly journals CRITÈRES D'IRRÉDUCTIBILITÉ POUR LES REPRÉSENTATIONS DES COURBES ELLIPTIQUES

2011 ◽  
Vol 07 (04) ◽  
pp. 1001-1032 ◽  
Author(s):  
NICOLAS BILLEREY
Keyword(s):  
Elliptic Curve ◽  
Prime Number ◽  
Number Field ◽  
Efficient Algorithm ◽  
Complex Multiplication ◽  
Prime Numbers ◽  
Prime Divisors ◽  
Numerical Examples ◽  
Finite Case ◽  
Courbe Elliptique

Soit E une courbe elliptique définie sur un corps de nombres K. On dit qu'un nombre premier p est réductible pour le couple (E, K) si E admet une p-isogénie définie sur K. L'ensemble de tous ces nombres premiers est fini si et seulement si E n'a pas de multiplication complexe définie sur K. Dans cet article, on montre que l'ensemble des nombres premiers réductibles pour le couple (E, K) est contenu dans l'ensemble des diviseurs premiers d'une liste explicite d'entiers (dépendant de E et de K) dont une infinité d'entre eux est non nulle. Cela fournit un algorithme efficace de calcul dans le cas fini. D'autres critères moins généraux, mais néanmoins utiles sont donnés ainsi que de nombreux exemples numériques. Let E be an elliptic curve defined over a number field K. We say that a prime number p is reducible for (E, K) if E admits a p-isogeny defined over K. The so-called reducible set of all such prime numbers is finite if and only if E does not have complex multiplication over K. In this paper, we prove that the reducible set is included in the set of prime divisors of an explicit list of integers (depending on E and K), infinitely many of them being non-zero. It provides an efficient algorithm for computing it in the finite case. Other less general but rather useful criteria are given, as well as many numerical examples.

Số nguyên tố an toàn trong các giao thức DH-KE

2020 ◽  
Vol 1 (11) ◽  
pp. 23-31
Author(s):  
Nguyễn Thanh Sơn
Keyword(s):  
Prime Numbers ◽  
Prime Divisors ◽  
Small Subgroup ◽  
Safe Primes

Tóm tắt—Việc sinh các số nguyên tố “an toàn” p, mà ở đó tất cả các ước nguyên tố khác 2 của p-1 đều là ước nguyên tố lớn, là hết sức cần thiết để tránh các tấn công nhóm con nhỏ được chỉ ra bởi hai tác giả Chao Hoom Lim và Pil Joong Lee. Một thuật toán hiện có để sinh các số nguyên tố như vậy cũng đã được trình bày bởi hai tác giả này. Tuy nhiên, hạn chế của phương pháp đó là thuật toán không phải khi nào cũng trả về được một số nguyên tố an toàn. Một phần lý do cho vấn đề này là vì thuật toán không (và khó có thể) được phân tích và đánh giá kỹ lưỡng về mặt toán học. Do đó, mục đích chính của bài báo là đề xuất một thuật toán mới để sinh các số nguyên tố an toàn và kèm theo các đánh giá chi tiết về mặt toán học.Abstract—The generate of “safe” primes p, where all prime divisors of p-1 are large prime divisors, is essential to avoid small subgroup attacks which are point out by two authors Chao Hoom Lim and Pil Joong Lee. An existing algorithm for generating such primes has also been presented by these two authors. However, the drawback of that method is that the algorithm does not always return safe prime numbers. Part of the reason for this is that the algorithm is not (and hardly) be thoroughly analyzed and evaluated mathematically. Therefore, the main purpose of this paper is to propose a new algorithm for generating safe prime numbers, including detailed mathematical evaluations.

On the Selmer Group of Twists of Elliptic Curves with Q-Rational Torsion Points

1988 ◽  
Vol 40 (3) ◽  
pp. 649-665 ◽  
Author(s):  
G. Frey
Keyword(s):  
Algebraic Number ◽  
Finite Extension ◽  
Algebraic Number Field ◽  
Prime Numbers ◽  
Selmer Group ◽  
Prime Divisors ◽  
Torsion Points ◽  
Root Of Unity ◽  
Finite Set ◽  
Image Position

(1) The symbols p and q stand for prime numbers and throughout the paper we assume that p is fixed and contained in {3, 5, 7}. Let L be an algebraic number field (i.e., L is a finite extension of Q). Then prime divisors of L dividing p (resp. q) are denoted by (resp. ). The completion of L with respect to is denoted by . Let S be a finite set of prime numbers, and let M/L be a Galois extension with abelian Galois group of exponent p.Definition. M/L is said to be little ramified outside S if for primes q ∉ S and all one haswith k ∊ N and . Here ζp is a pth root of unity, u1, …, uk are elements in and is the normed valuation belonging to . In particular M/L is unramified at all divisors of primes q ∉ S ∪ {p}.

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