This page intentionally left blank Elementary Number Theory in Nine Chapters Elementary Number Theory in Nine Chapters Second Edition JAMES J. TATTERSALL Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press TheEdinburghBuilding,Cambridge,UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridg e.org /9780521850148 © Cambridge University Press 2005 Thispublicationisincopyright.Subjecttostatutoryexceptionandtotheprovisionof relevantcollectivelicensingagreements,noreproductionofanypartmaytakeplace without the written permission of Cambridge University Press. Firstpublishedinprintformat 2005 - ---- eBook(EBL) - --- eBook(EBL) - ---- hardback - --- hardback - ---- paperback - --- paperback CambridgeUniversityPresshasnoresponsibilityforthepersistenceoraccuracyofs forexternalorthird-partyinternetwebsitesreferredtointhispublication,anddoesnot guaranteethatanycontentonsuchwebsitesis,orwillremain,accurateorappropriate. ToTerry Contents Preface pageix 1 Theintriguingnaturalnumbers 1.1 Polygonalnumbers 1 1.2 Sequencesofnaturalnumbers 23 1.3 Theprincipleofmathematicalinduction 40 1.4 Miscellaneousexercises 43 1.5 Supplementaryexercises 50 2 Divisibility 2.1 Thedivisionalgorithm 55 2.2 Thegreatestcommondivisor 64 2.3 TheEuclideanalgorithm 70 2.4 Pythagoreantriples 76 2.5 Miscellaneousexercises 81 2.6 Supplementaryexercises 84 3 Primenumbers 3.1 Euclidonprimes 87 3.2 Numbertheoreticfunctions 94 3.3 Multiplicativefunctions 103 3.4 Factoring 108 3.5 Thegreatestintegerfunction 112 3.6 Primesrevisited 115 3.7 Miscellaneousexercises 129 3.8 Supplementaryexercises 133 vi Contents vii 4 Perfectandamicablenumbers 4.1 Perfectnumbers 136 4.2 Fermatnumbers 145 4.3 Amicablenumbers 147 4.4 Perfect-typenumbers 150 4.5 Supplementaryexercises 159 5 Modulararithmetic 5.1 Congruence 161 5.2 Divisibilitycriteria 169 5.3 Euler’sphi-function 173 5.4 Conditionallinearcongruences 181 5.5 Miscellaneousexercises 190 5.6 Supplementaryexercises 193 6 Congruencesofhigherdegree 6.1 Polynomialcongruences 196 6.2 Quadraticcongruences 200 6.3 Primitiveroots 212 6.4 Miscellaneousexercises 222 6.5 Supplementaryexercises 223 7 Cryptology 7.1 Monoalphabeticciphers 226 7.2 Polyalphabeticciphers 235 7.3 Knapsackandblockciphers 245 7.4 Exponentialciphers 250 7.5 Supplementaryexercises 255 8 Representations 8.1 Sumsofsquares 258 8.2 Pell’sequation 274 8.3 Binaryquadraticforms 280 8.4 Finitecontinuedfractions 283 8.5 Infinitecontinuedfractions 291 8.6 p-Adicanalysis 298 8.7 Supplementaryexercises 302 viii Contents 9 Partitions 9.1 Generatingfunctions 304 9.2 Partitions 306 9.3 PentagonalNumberTheorem 311 9.4 Supplementaryexercises 324 Tables T.1 Listofsymbolsused 326 T.2 Primeslessthan10000 329 T.3 Thevaluesof(cid:1)(n),(cid:2)(n),(cid:3)(n), (cid:4)(n),ø(n), and(cid:1)(n)fornaturalnumberslessthanor equalto100 333 Answerstoselectedexercises 336 Bibliography Mathematics(general) 411 History(general) 412 Chapterreferences 413 Index 421
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