So having discussed the weird and the untouchable, its time to check in with the grandaddy of all proper divisorrelated numbers. All 4 digit palindromic numbers are divisible by 11. Abundant numbers, also known as excessive, are bigger than the sum of their proper divisors. Since ancient times, people have separated the natural numbers into a variety of different types. These notes were prepared by joseph lee, a student in the class, in collaboration with prof. An example is checking whether universal product codes upc or international standard book number isbn codes are legitimate. As a rule, these theories are developed sufficiently far so that the.
It covers the basic background material that an imo student should be familiar with. An example is checking whether universal product codes upc or international standard book number isbn codes are legiti mate. A bit expensive, but if you want to own one book on elementary number theory, this ones a pretty good candidate. Well, to be fair, mltt is built on top of a theory of conjunction and implication, but the only theorem of that theory is so i dont really think it counts. Note that these problems are simple to state just because a topic is accessibile does not mean that it is easy. A positive integer n is weird if the sum of the proper divisors of n exceeds n. We begin with an important divisibility property of primes. The websites by chris caldwell 2 and by eric weisstein are especially good. In this volume, wellknown number theorist, melvyn b. He escapes, and disguises himself as 46 to explain the system of rational numbers and the concept of equivalent fractions. In number theory, a weird number is a natural number that is abundant but not semiperfect in other words, the sum of the proper divisors divisors including 1 but not itself of the number is greater than the number, but no subset of those divisors sums to the number itself. Introduction to number theory and its applications lucia moura winter 2010 \mathematics is the queen of sciences and the theory of numbers is the queen of mathematics. To understand them, we must first begin with abundant numbers. We next show that all ideals of z have this property.
I was able to find one reference cn friedman, sums of divisors and egyptian fractions,journal of number theory 1993 which shows the weak lower bound of 2 32. In this paper we study some structure properties of primitive weird numbers in terms of their factorization. Constructing picard curves with complex multiplication using the chinese remainder theorem. Why 5, 8 and 24 are the strangest numbers in the universe.
The weird number, 23, steals a piece of cake and then leads the townspeople on a merry chase. The proof of the other assertions is left to the reader. Probability theory is the most directly relevant mathematical background, and it is assumed that the reader has a working knowledge of measuretheorybased probability theory. In fact, it is typical statistical agency practice to pick a basket that pertains to an entire year or. Now every integer divides zero, so that if a b 0, then every integer serves as a common divisor of a and b. Gioia the theory of numbers markham publishing company 1970 acrobat 7 pdf 6. The first perfect number is 6, as its divisors 1, 2, 3 all up to 6. Preface these are the notes of the course mth6128, number theory, which i taught at queen mary, university of london, in the spring semester of 2009. So, for example, number theory is very much relevant to m. As it holds the foundational place in the discipline, number theory is also called the queen of mathematics. For example, here are some problems in number theory that remain unsolved.
A rational number is a number which can be expressed as the ratio a b of two integers a,b, where b 6 0. Analytic number theory a tribute to gauss and dirichlet 7 ams cmi duke and tschinkel, editors 264 pages on 50 lb stock 12 inch spine analytic number theory a tribute to gauss and dirichlet william duke yuri tschinkel editors cmip7. In number theory, a weird number is a natural number that is abundant but not semiperfect. Note that these problems are simple to state just because a. To find all of the prime numbers between 1 and 100, complete the following exercise. This chapter lays the foundations for our study of the theory of numbers by weaving together the themes of prime numbers, integer factorization, and the distribution of primes.
Secret link uncovered between pure math and physics. When two elements, x 1 6 x 2 hash to the same value, we call it a collision. Find materials for this course in the pages linked along the left. Divisibility is an extremely fundamental concept in number theory, and has applications including puzzles, encrypting messages, computer security, and many algorithms. Olympiad number theory through challenging problems. Notice that apart from 2, all primes are odd since every even integer is divisible by 2. Recall that a prime number is an integer greater than 1 whose only positive factors are 1 and the number itself. The result is indeed true and follows from the next theorem. Applications cse235 introduction hash functions pseudorandom numbers representation of integers euclids algorithm c. A perfect number is one that is exactly equal to the sum of its proper divisors again, excluding itself.
In particular, if we are interested in complexity only up to a. What are the weirdest mathematical theories you know. Any weirdness has more to do with my poor interpretation of the theorem than. Questions based on various concepts of number theory and different types of number are quite frequently asked in programming contests. What are the \objects of number theory analogous to the above description.
In the may 2011 issue of scientific american mathematician john baez coauthors the strangest numbers in string theory, an article about the octonions, an eightdimensional number system that. Depending on the value of k, the innermost computation of the recursion. We give sufficient conditions to ensure that a positive integer is weird. The result will will be divisible by 7, 11 and, and dividing by all three will give your original threedigit number. A good one sentence answer is that number theory is the study of the integers, i. Cryptography hash functions iii however, the function is clearly not onetoone. We list some simple properties of divisibility for numbers x,y,z. One of the most common hash functions uses modular arithmetic. Basic index number theory 371 approaches are also possible. If n is an odd prime number, then n divides the left band side, so it must divide one of the three factors on the right.
Standard applications of number theory are to computer science and cryptology. In the 1970s, three mathematicians at mit showed that his discovery could be used to formulate a remarkably powerful method for encrypting information to be sent online. Syllabus theory of numbers mathematics mit opencourseware. It covers the basic background material that an imo student should be familiar.
Nov 29, 2018 a possible clue from the cicada 3301 puzzle. This is quite comprehensive and has a nice collection of topics and exercises. Given a natural number n, if n is prime, then it is the product of just one prime. Number theory is the study of the set of positive whole numbers 1. A computational introduction to number theory and algebra. Whereas one of the principal concerns of the latter theory is the deconposition of numbers into prime factors, additive number theory deals with the decomposition of numbers into summands. The euclidean algorithm and the method of backsubstitution 4 4. Nathanson, gathers articles from the workshop on other, less standard applications in number theory, as well as topics in number theory with potential applications in science and engineering. In this article, we discuss some famous facts and algorithms. Number theory is a branch of pure mathematics devoted to the study of the natural numbers and the integers. Number theory naoki sato 0 preface this set of notes on number theory was originally written in 1995 for students at the imo level. Dec 09, 2012 cryptography and number theory over 300 years ago, a mathematician named fermat discovered a subtle property about prime numbers.
By the fundamental theorem of arithmetic, n is divisible by some prime p. Mathematics is full of weird number systems that most people have never heard of and would have trouble even conceptualizing. Two algorithms for generating weird numbers having a given number of distinct prime factors are presented. Chapter 1 covers this theory at a fairly rapid pace. That being said, it is hard for me to ever finding anything weird in math. This discipline of number theory investigates to what extent real numbers can be approximated by fractions.
The ideals that are listed in example 4 are all generated by a single number g. Show that if a and b are positive integers where a is even and b is odd, then. We will encounter all these types of numbers, and many others, in our excursion through the theory of numbers. This book was written as a text for the learning of number theory, not as a referente. If ais not equal to the zero ideal f0g, then the generator gis the smallest positive integer belonging to a. Under the assumptions of problem 11, find the number of solutions to the. We prove dirichlets theorem which says that every irrational number can be approximated by in. May 04, 2011 in the may 2011 issue of scientific american mathematician john baez coauthors the strangest numbers in string theory, an article about the octonions, an eightdimensional number system that.
Cryptography and number theory over 300 years ago, a mathematician named fermat discovered a subtle property about prime numbers. To see what is going on at the frontier of the subject, you may take a look at some recent issues of the journal of number theory which you will. Basic algorithms in number theory 27 the size of an integer x is o. It is the study of the set of positive whole numbers which are usually called the set of natural numbers. The number eld sieve is the asymptotically fastest known algorithm for factoring general large integers that dont have too special of a form. Proof we show the existence of a factorisation into primes by induction. Basic algorithms in number theory universiteit leiden. In other words, the sum of the proper divisors divisors including 1 but not itself of the number is greater than the number, but no subset of those divisors sums to the number itself. We prove that the density of weird numbers is positive and discuss several related prob lems and. It isnt completely clear to me what relevant means in this context, since usually when we say that something is relevant, we mean to say that it is relevant to something in particular. Primitive weird numbers having more than three distinct. However, when at least one of a or b is different from zero, there are only a finite number of positive common divisors. In this instance, the set of positive common divisors of a and b is infinite.1136 424 413 1193 823 1443 550 178 701 320 742 1289 417 1072 594 1049 658 11 880 1382 41 1613 401 756 950 138 90 1079 935 1226 594 1616 1499 631 434 1025 1258 354 1303 650 365 928 1422 697