<p>Preface</p> <p>Flowchart of Chapter Dependencies</p> <p>Introduction</p> <p>1. What Is Number Theory?</p> <p>2. Pythagorean Triples</p> <p>3. Pythagorean Triples and the Unit Circle</p> <p>4. Sums of Higher Powers and Fermat’s Last Theorem</p> <p>5. Divisibility and the Greatest Common Divisor</p> <p>6. Linear Equations and the Greatest Common Divisor</p> <p>7. Factorization and the Fundamental Theorem of Arithmetic</p> <p>8. Congruences</p> <p>9. Congruences, Powers, and Fermat’s Little Theorem</p> <p>10. Congruences, Powers, and Euler’s Formula</p> <p>11. Euler’s Phi Function and the Chinese Remainder Theorem</p> <p>12. Prime Numbers</p> <p>13. Counting Primes</p> <p>14. Mersenne Primes</p> <p>15. Mersenne Primes and Perfect Numbers</p> <p>16. Powers Modulo m and Successive Squaring</p> <p>17. Computing k<sup>th</sup> Roots Modulo m</p> <p>18. Powers, Roots, and “Unbreakable” Codes</p> <p>19. Primality Testing and Carmichael Numbers</p> <p>20. Squares Modulo p</p> <p>21. Quadratic Reciprocity</p> <p>22. Proof of Quadratic Reciprocity</p> <p>23. Which Primes Are Sums of Two Squares?</p> <p>24.Which Numbers Are Sums of Two Squares?</p> <p>25. Euler’s Phi Function and Sums of Divisors</p> <p>26. Powers Modulo p and Primitive Roots</p> <p>27. Primitive Roots and Indices</p> <p>28. The Equation X<sup>4</sup> + Y<sup>4</sup> = Z<sup>4</sup></p> <p>29. Square–Triangular Numbers Revisited</p> <p>30. Pell’s Equation</p> <p>31. Diophantine Approximation</p> <p>32. Diophantine Approximation and Pell’s Equation</p> <p>33. Number Theory and Imaginary Numbers</p> <p>34. The Gaussian Integers and Unique Factorization</p> <p>35. Irrational Numbers and Transcendental Numbers</p> <p>36. Binomial Coefficients and Pascal’s Triangle</p> <p>37. Fibonacci’s Rabbits and Linear Recurrence Sequences</p> <p>38. Cubic Curves and Elliptic Curves</p> <p>39. Elliptic Curves with Few Rational Points</p> <p>40. Points on Elliptic Curves Modulo p</p> <p>41. Torsion Collections Modulo p and Bad Primes</p> <p>42. Defect Bounds and Modularity Patterns</p> <p>43. Elliptic Curves and Fermat’s Last Theorem</p> <p> </p> <p>Index</p> <p> </p> <p>*47. The Topsy-Turvey World of Continued Fractions [online]</p> <p>*48. Continued Fractions, Square Roots, and Pell’s Equation [online]</p> <p>*49. Generating Functions [online]</p> <p>*50. Sums of Powers [online]</p> <p>*A. Factorization of Small Composite Integers [online]</p> <p>*B. A List of Primes [online]</p> <p> </p> <p>*These chapters are available online</p>